Technology Research for Rotor Wedge Installation of Hydrogenerator
Issue:
Volume 7, Issue 3, September 2021
Pages:
97-102
Received:
30 May 2021
Accepted:
17 June 2021
Published:
8 July 2021
Abstract: When the rotor of the hydroelectric generator is running, the centrifugal force of the rotor rim is very high. Centrifugal force will produce obvious radial deformation on the rotor rim lamination, which will cause a radial separation gap between the rim and the rotor spider. The larger the diameter of the rotor, the larger the separation gap, therefore, when the rotor is assembled, each component is required to have sufficient strength, good balance and integrity. In order to ensure the stability and balance of the rim during the installation, it is necessary to focus on the technical measures to control installation of the wedges, to complete the thermal keying operations in strict accordance with the requirements. The purpose of the rotor thermal keying is to maintain the safety and stability during operation, to facilitate rim and rotor hub to be closely combined, and to achieve a reliable cooperation between them. A certain amount of mechanical compression is applied simultaneously between rim and rotor spider, which can generally be achieved by thermal keying or conventional rim hot keying on the basis of cold keying, the rim is heated to generate gap between rotor rim and hub, the keys are driven to the gap in specified depth. After the rotor rim is cooled down, the effective coordination between rotor rim and rotor hub can be ensured, the centripetal force generated during the operation of the unit can be offset to maintain the unit’s reliable operation. The installation of hydro-generator rotor’s wedge is an important process, it's a matter of the roundness and concentricity, higher requirements is needed for large capacity generators. Based on the structural characteristics of the rotor installed at the Ludila Power Station on the Jinsha River, this article introduces the installation and welding process of the wedges for the rotor at the Ludila Power Station, as well as the difference between thermal keying technology and conventional rim hot keying. Quality control, installing procedure and methods for installation of rotor wedge are described. This article could provide guidance and reference for the implementation of similar projects, research on new advanced technology for the industry.
Abstract: When the rotor of the hydroelectric generator is running, the centrifugal force of the rotor rim is very high. Centrifugal force will produce obvious radial deformation on the rotor rim lamination, which will cause a radial separation gap between the rim and the rotor spider. The larger the diameter of the rotor, the larger the separation gap, ther...
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Forecasting of Monthly Flow for the White Nile River (South Sudan)
Issue:
Volume 7, Issue 3, September 2021
Pages:
103-112
Received:
31 March 2021
Accepted:
22 April 2021
Published:
18 August 2021
Abstract: Forecasting of monthly streamflow for the White Nile River at Malakal station is a crucial aspect for different water resources projects in both countries Sudan and South Sudan. For instance, the operation of Jabal al Awliya dam in central Sudan entirely depends upon the measured flow of this station. In this paper, linear stochastic models well-known as seasonal autoregressive integrated moving average [SARIMA] models were used to model and forecast monthly flow of White Nile River in Malakal station, South Sudan. For the analysis, monthly flow data for the years running from 1970 up to 2013 were used. A scrutiny of the original series proves a yearly seasonal pattern. The results of Phillips-Perron (PP) test and Augmented Dickey Fuller (ADF) test on the streamflow series show that this series is not stationary. This non-stationarity was removed using first order seasonal differencing (i.e. twelve-monthly) preceding to the development of the model. The SARIMA (1,0,1)×(0,1,1)12 model was selected as the most suitable for modeling and forecasting monthly flow for White Nile River. It was found that the model was proper to forecast three successive years of monthly flow, which may help the experts to institute priorities for various water resources management in both countries.
Abstract: Forecasting of monthly streamflow for the White Nile River at Malakal station is a crucial aspect for different water resources projects in both countries Sudan and South Sudan. For instance, the operation of Jabal al Awliya dam in central Sudan entirely depends upon the measured flow of this station. In this paper, linear stochastic models well-kn...
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Hydrogeochemistry and Health Risks Assessment of Some Groundwaters Suitability for Drinking Within the Urban Region of Unguja Island, Zanzibar
Ochieng O. Anthony,
Ali Salim Ali,
Hekimani Seif Hamad,
Mariam Khamis Hamad,
Khamis Abubakar Juma
Issue:
Volume 7, Issue 3, September 2021
Pages:
113-125
Received:
25 August 2021
Accepted:
6 September 2021
Published:
10 September 2021
Abstract: Majority of the Island inhabitants depends on groundwaters for drinking therefore the hydrogeochemistry and health risks assessment with respect to WHO standards is absolutely essential for protection policy formulation. The groundwater samples for analyses were collected from selected four wells within each (Chukwani-Mbweni, DarajaMbovu - Amani and Mwanakwerekwe) suburb during the moderate rainy season of January 2020. The selection was based on their strategic positions taking into consideration relevant geographical and environmental factors commensurable with this study. Various contaminants and physiochemical parameters were determined using Atomic Absorption spectroscopy, GC/MS, Temp/pH/TDS/EC meter and DR/3900 spectrophotometer. Chemical Oxygen Demand values were also determined. Microbial contamination was determined using the MPN technique. The results show that these groundwaters are slightly alkaline, microbially contaminated, have high C.O.D. values ranging from 188.5 to 305.7 mg/L indicating the existence of some organic based endocrine disruptive elements, and disparities in water quality parameters with respect to the recommended WHO standards thus ascertaining possible public health risks. The research recommends the need for continuous monitoring, assessment and treatment of these raw groundwaters for drinking at the point of collection rather relying on the old conventional boiling method or drinking as it is.
Abstract: Majority of the Island inhabitants depends on groundwaters for drinking therefore the hydrogeochemistry and health risks assessment with respect to WHO standards is absolutely essential for protection policy formulation. The groundwater samples for analyses were collected from selected four wells within each (Chukwani-Mbweni, DarajaMbovu - Amani an...
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