Dry Gas Face Seal Design With Arbitrary Gap Shape

2017 ◽  
Author(s):  
Aleksandr S. Vinogradov ◽  
Sergey V. Falaleev ◽  
Renat B. Badykov
Keyword(s):  
Analytical Calculation ◽  
Turbine Engines ◽  
Worst Case ◽  
Practical Result ◽  
Seal Design ◽  
Gas Seals ◽  
Gas Pumping ◽  
Gas Pumping Unit ◽  
Gas Face Seal ◽  
The Impact

Active use of dry gas seals for gas turbine engines is constrained by several important factors. One of them is a significant deformation of the sealing rings. This paper is dedicated to the creation of a technique of designing of a dry gas seal with spiral grooves with a consideration of arbitrary gap shape. A large number of studies for this type of seal have been conducted. But the technique of the seal designing which combines sealing leakage calculation with the calculation of the actual rings deformation has not been implemented. This article proposes a solution for this significant problem. Indeed, the increase in temperature and pressure drop results in a deformation of the rings surfaces. For the small gap, the impact of force and thermal deformation is critical. The seal designing without consideration of the surfaces deformation can lead to significant errors, but also to the failure of the seal in operation in the worst case. An improved mathematical model for calculating the leakage is proposed. On its basis, the designing technique has been developed. This technique combines the analytical calculation and calculation of deformation by finite element method. Implementation of this technique has a good practical result. The seal was created for a gas pumping unit. Experimental results have confirmed the computational results.

scholarly journals SPE “Mashproekt” Gas Turbine Engines for Gas Pumping Sets

1996 ◽  
Author(s):  
Victor I. Romanov ◽  
Vladimir V. Lupandin ◽  
Anatoliy V. Kovalenko ◽  
Anatoliy I. Shelestyuk
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Test Bed ◽  
Technical Data ◽  
Gas Pumping ◽  
Gas Pumping Unit ◽  
Pumping Units ◽  
Gas Loop

The paper describes the experience gained in designing, developing and operation of gas turbine engines for gas pumping units on the marine gas turbine engine’s base. More than 800 Mashproekt gas turbines of various power output have been in service in gas pumping application since 1980. This paper shows the SPE Mashproekt designing and developing approach for gas turbines to be installed in gas pumping units along with their full-scale testing in the test bed of close gas loop type equipped with gas compressor and gas coolers to simulate operation of the gas pumping unit in the real gas pipeline conditions. The gas turbines for gas pumping application on the 2.5 MW, 6 MW, 10 MW, 16 MW and 25 MW engines base were developed in the period of 1990–1995 for replacement of the existing old gas turbine line-up and installation in the new gas pumping units at the compressor stations in Russia and Ukraine. We are replacing engines with Mashproekt gas turbines at the following gas pumping units: Russian GTN-25, Ukrainian GPA-6.3, GPA-16 and “Coberra-182” (Great Britain) gas pumping units. The comparison of the technical characteristics of these replacements is given in the paper. Technical data on 2.5–25 MW Mashproekt gas turbines for gas pumping units is also presented in this paper.

scholarly journals Reducing environmental impacts from garments through best practice garment use and care, using the example of a Merino wool sweater

2021 ◽  
Author(s):  
Stephen G. Wiedemann ◽  
Leo Biggs ◽  
Quan V. Nguyen ◽  
Simon J. Clarke ◽  
Kirsi Laitala ◽  
...  
Keyword(s):  
Environmental Impacts ◽  
Energy Demand ◽  
Best Practice ◽  
Western Europe ◽  
Impact Category ◽  
Fashion Industry ◽  
Worst Case ◽  
Multiple Users ◽  
Washing Machines ◽  
The Impact

Abstract Purpose Garment production and use generate substantial environmental impacts, and the care and use are key determinants of cradle-to-grave impacts. The present study investigated the potential to reduce environmental impacts by applying best practices for garment care combined with increased garment use. A wool sweater is used as an example because wool garments have particular attributes that favour reduced environmental impacts in the use phase. Methods A cradle-to-grave life cycle assessment (LCA) was used to compare six plausible best and worst-case practice scenarios for use and care of a wool sweater, relative to current practices. These focussed on options available to consumers to reduce impacts, including reduced washing frequency, use of more efficient washing machines, reduced use of machine clothing dryers, garment reuse by multiple users, and increasing number of garment wears before disposal. A sixth scenario combined all options. Worst practices took the worst plausible alternative for each option investigated. Impacts were reported per wear in Western Europe for climate change, fossil energy demand, water stress and freshwater consumption. Results and discussion Washing less frequently reduced impacts by between 4 and 20%, while using more efficient washing machines at capacity reduced impacts by 1 to 6%, depending on the impact category. Reduced use of machine dryer reduced impacts by < 5% across all indicators. Reusing garments by multiple users increased life span and reduced impacts by 25–28% across all indicators. Increasing wears from 109 to 400 per garment lifespan had the largest effect, decreasing impacts by 60% to 68% depending on the impact category. Best practice care, where garment use was maximised and care practices focussed on the minimum practical requirements, resulted in a ~ 75% reduction in impacts across all indicators. Unsurprisingly, worst-case scenarios increased impacts dramatically: using the garment once before disposal increased GHG impacts over 100 times. Conclusions Wool sweaters have potential for long life and low environmental impact in use, but there are substantial differences between the best, current and worst-case scenarios. Detailed information about garment care and lifespans is needed to understand and reduce environmental impacts. Opportunities exist for consumers to rapidly and dramatically reduce these impacts. The fashion industry can facilitate this through garment design and marketing that promotes and enables long wear life and minimal care.

scholarly journals Adaptive Robust Optimization-Based Optimal Operation of Microgrids Considering Uncertainties in Arrival and Departure Times of Electric Vehicles

Energies ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2646 ◽  
Author(s):  
Se-Hyeok Choi ◽  
Akhtar Hussain ◽  
Hak-Man Kim
Keyword(s):  
Robust Optimization ◽  
Electric Vehicles ◽  
Unit Commitment ◽  
Renewable Energy Sources ◽  
Market Price ◽  
Optimal Operation ◽  
Worst Case ◽  
Price Signals ◽  
Power Trading ◽  
The Impact

The optimal operation of microgrids is challenging due to the presence of various uncertain factors, i.e., renewable energy sources, loads, market price signals, and arrival and departure times of electric vehicles (EVs). In order to incorporate these uncertainties into the operation model of microgrids, an adaptive robust optimization-based operation method is proposed in this paper. In particular, the focus is on the uncertainties in arrival and departure times of EVs. The optimization problem is divided into inner and outer problems and is solved iteratively by introducing column and constraint cuts. The unit commitment status of dispatchable generators is determined in the outer problem. Then, the worst-case realizations of all the uncertain factors are determined in the inner problem. Based on the values of uncertain factors, the generation amount of dispatchable generators, the amount of power trading with the utility grid, and the charging/discharging amount of storage elements are determined. The performance of the proposed method is evaluated using three different cases, and sensitivity analysis is carried out by varying the number of EVs and the budget of uncertainty. The impact of the budget of uncertainty and number of EVs on the operation cost of the microgrid is also evaluated considering uncertainties in arrival and departure times of EVs.

scholarly journals Assessing storm surge hazard and impact of sea level rise in the Lesser Antilles case study of Martinique

2017 ◽  
Vol 17 (9) ◽  
pp. 1559-1571 ◽  
Author(s):  
Yann Krien ◽  
Bernard Dudon ◽  
Jean Roger ◽  
Gael Arnaud ◽  
Narcisse Zahibo
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Storm Surge ◽  
Numerical Models ◽  
Lesser Antilles ◽  
Adaptation Measures ◽  
Worst Case ◽  
Mitigation And Adaptation ◽  
The Impact

Abstract. In the Lesser Antilles, coastal inundations from hurricane-induced storm surges pose a great threat to lives, properties and ecosystems. Assessing current and future storm surge hazards with sufficient spatial resolution is of primary interest to help coastal planners and decision makers develop mitigation and adaptation measures. Here, we use wave–current numerical models and statistical methods to investigate worst case scenarios and 100-year surge levels for the case study of Martinique under present climate or considering a potential sea level rise. Results confirm that the wave setup plays a major role in the Lesser Antilles, where the narrow island shelf impedes the piling-up of large amounts of wind-driven water on the shoreline during extreme events. The radiation stress gradients thus contribute significantly to the total surge – up to 100 % in some cases. The nonlinear interactions of sea level rise (SLR) with bathymetry and topography are generally found to be relatively small in Martinique but can reach several tens of centimeters in low-lying areas where the inundation extent is strongly enhanced compared to present conditions. These findings further emphasize the importance of waves for developing operational storm surge warning systems in the Lesser Antilles and encourage caution when using static methods to assess the impact of sea level rise on storm surge hazard.

scholarly journals Improving the Efficiency of Gas Pumping Units: Problems and Solutions

2019 ◽  
pp. 104-118
Author(s):  
E.M. Komarov ◽  
Zh.M. Kokueva
Keyword(s):  
Gas Turbine ◽  
Problems And Solutions ◽  
Pumping Unit ◽  
Gas Pumping ◽  
Gas Pumping Unit ◽  
Pumping Units ◽  
Turbine Drive

The paper describes the process of initiating a project to improve the efficiency of gas turbine plants for driving centrifugal superchargers at compressor stations. The study shows the main trends of increasing the efficiency of gas turbine drives of gas pumping units, gives the constructive-functional appearance of the modern gas turbine drive of the gas pumping unit, and proposes a method for increasing its efficiency.

scholarly journals 1628 Vaccination for Safe Surgery During The SARS-Cov-2 Pandemic: Modelling Study

2021 ◽  
Vol 108 (Supplement_6) ◽  
Author(s):  
Keyword(s):  
General Population ◽  
Elective Surgery ◽  
Risk Difference ◽  
Cancer Surgery ◽  
Number Needed To Treat ◽  
Worst Case ◽  
Registration Data ◽  
Increased Risk ◽  
One Year ◽  
The Impact

Abstract Introduction Compared to the general population, in the postoperative period, surgical patients are both at increased risk of SARS-CoV-2 infection and increased mortality in the event of SARS-CoV-2 infection. This study modelled the impact of preoperative vaccination of patients aged ≥70 years having elective inpatient surgery. Method The primary outcome was the number needed to treat (NNT) to prevent one death over one year following SARS-CoV-2 vaccination. Postoperative SARS-CoV-2 incidence and adjusted mortality risk difference for SARS-CoV-2 infection were estimated from the prospective GlobalSurg-CovidSurg Week study (90,146 elective surgery patients across 1,595 hospitals in 115 countries), were used to estimate lives saved by vaccination in the first 30 postoperative days. SARS-CoV-2 case and death registration data from the Office for National Statistics was used to estimate NNTs for the general population. Best and worst-case scenarios were used to describe uncertainty around estimates. Results Among patients aged ≥70 years undergoing any type of surgery, NNT was estimated to be 332 (best case: 213; worst case: 690). NNT was lower in the cancer surgery subgroup (245 [150-545]). This was more favourable than the NNT for vaccination of the general population aged ≥70 (588 [403-1032]). Globally, vaccinating elective surgery patients aged ≥70 years preoperatively was projected to save 27,356 lives in one year compared to vaccinating the same patients after surgery. Conclusions Preoperative pathways should be set up for the vaccination of patients aged ≥70. In settings with limited vaccine availability, elective cancer surgery patients should be prioritised for vaccination.

scholarly journals SPATIOTEMPORAL VISUALIZATION OF TSUNAMI WAVES USING KML ON GOOGLE EARTH

2017 ◽  
Vol XLII-2/W7 ◽  
pp. 1291-1299 ◽  
Author(s):  
H. Mohammadi ◽  
M. R. Delavar ◽  
M. A. Sharifi ◽  
M. D. Pirooz
Keyword(s):  
Decision Making ◽  
Disaster Management ◽  
Google Earth ◽  
Disaster Mitigation ◽  
Case Scenario ◽  
Worst Case ◽  
Tsunami Waves ◽  
Spatiotemporal Visualization ◽  
Virtual Globes ◽  
The Impact

Disaster risk is a function of hazard and vulnerability. Risk is defined as the expected losses, including lives, personal injuries, property damages, and economic disruptions, due to a particular hazard for a given area and time period. Risk assessment is one of the key elements of a natural disaster management strategy as it allows for better disaster mitigation and preparation. It provides input for informed decision making, and increases risk awareness among decision makers and other stakeholders. Virtual globes such as Google Earth can be used as a visualization tool. Proper spatiotemporal graphical representations of the concerned risk significantly reduces the amount of effort to visualize the impact of the risk and improves the efficiency of the decision-making process to mitigate the impact of the risk. The spatiotemporal visualization of tsunami waves for disaster management process is an attractive topic in geosciences to assist investigation of areas at tsunami risk. In this paper, a method for coupling virtual globes with tsunami wave arrival time models is presented. In this process we have shown 2D+Time of tsunami waves for propagation and inundation of tsunami waves, both coastal line deformation, and the flooded areas. In addition, the worst case scenario of tsunami on Chabahar port derived from tsunami modelling is also presented using KML on google earth.

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