Geothermal Energy Training and Research Institute
http://repository.dkut.ac.ke:8080/xmlui/handle/123456789/707
2024-03-28T10:30:28ZImprovement Of Ring Frame Spindle Utilization In Short Staple Spinning: A Case Study Of A Cotton Spinning Mill
http://repository.dkut.ac.ke:8080/xmlui/handle/123456789/4622
Improvement Of Ring Frame Spindle Utilization In Short Staple Spinning: A Case Study Of A Cotton Spinning Mill
Musyoki, Joseph Kivuva
Spinning mills in Kenya are operated by eight integrated textile industries to produce cotton yarns for internal use by their knitting and weaving departments and for sale to the local market. Fabric requirement estimated at 225 million square meters cannot be supplied by local domestic production and the gap is met through importation of fabrics and finished garments. Spinning mills play a very significant role in backward integration of the textile value chain by converting fibres into yarn for fabric production. Ring spinning is the most widely used cotton short staple spinning system to produce yarn from cotton fibers and is used by 7 of the 8 spinning mills. In Kenya, spinning mills have been operating at spindle utilisation between 67 to 80% which is below the recommended standard norm of 98%. The mills have been experiencing yarn production loss occurring from frequent stoppages of the ring frame and increase in the number of spindles running without producing yarn reducing the ring frame spindle hours used for yarn production. The overall objective of this study was to improve ring frame spindle utilisation in terms of spindle hours utilized for yarn production in cotton short staple spinning, a case study of Sunflag Textile and Knitwear Ltd. The specific objectives were to analyze ring spinning process production parameters, evaluate the factors affecting ring frame spindle utilisation and formulate a productivity improvement method for the mill.
The Research design adopted by this study was a descriptive and quantitative case study. Pareto analysis was used to classify ring frame production losses based on Overall Equipment Effectiveness (OEE) classification of major losses and Ishikawa diagram used to carry out Root Cause Analysis of main causes of production loss. Failure Mode and Effects Analysis (FMEA) technique was used to map the failures which occurred within the process that contributed to production loss which were ranked using their Risk Priority Numbers (RPN). A questionnaire based on Grunberg Performance Improvement Method (PIM) was used to analyse and evaluate mill production and management practices. A production improvement method was recommended using 7 evaluation criteria of the PIM. Pareto analysis revealed that Idling and minor stoppages accounted for 63% losses while breakdown accounted for 22.8% of losses. Root Cause Analysis (RCA) identified Manual doffing, lack of time awareness, and delay in replacement of empty bobbins as significant factors that affected ring frame doffing stoppage loss. It was recommended that a standardized procedure Single Minute Exchange of a Die (SMED) technique for the doffing procedure would yield the highest results in minimizing ring frame stoppage. A key finding from the study showed that utilisation of equipment for production in manufacturing was not just the overall time the machine was running, but about standardization of the entire process of production to maximize utilization of the machine for output. Through this study, spinning mills in Kenya can apply the recommendations to improve ring frame productivity in order to reduce the cost of production and improve their competitiveness.
2019-03-01T00:00:00ZModeling H2s Dispersion From Proposed Menengai Geothermal Powerplant
http://repository.dkut.ac.ke:8080/xmlui/handle/123456789/4621
Modeling H2s Dispersion From Proposed Menengai Geothermal Powerplant
Nyairo, Beatrice Kerubo
The Hydrogen sulfide gas released from the geothermal operations has a potential impact on the health of the workers and the community living within the vicinity and also the geothermal equipment. Similarly, this gas is a toxic pollutant when released into the atmosphere. Additionally, this gas is corrosive to metal-based materials including brass and iron when dissolved in water. In this regard, there is need to manage the concentrations of hydrogen sulfide in the atmosphere at acceptable levels without detrimental effects to components of the biosphere. The purpose of the research was to assess the concentrations of hydrogen sulfide within the vicinity of the power plant by use of a dispersion model.
The technique is carried out using atmospheric dispersion modeling system (AERMOD) which is a steady-state Gaussian model to determine the hydrogen sulfide concentrations in the atmosphere within the vicinity of the power plant. To achieve this goal, hourly meteorological data were captured and input to the Aermet processor. Since weather conditions heavily influence H2S concentration, statistical analysis was used to determine a correlation between the weather parameters and H2S concentration. As such, it provided a basis to determine the likelihood of conditions that may exceed the recommended concentrations and their potential effects on the environment. The prepared background and predictive model when combined show that although operations at Menengai Geothermal Project emit H2S gas, the concentrations are below the WHO set guidelines of 150 μg m-3 and therefore have a less impact on air quality. This research contributes to theory since no previous modeling on hydrogen sulphide gas has been done in Menengai. The findings are beneficial as part of regulations for air quality standards to reduce global warming and environmental degradation, the introduction of H2S abatement techniques and reduction strategies.
2018-12-01T00:00:00ZLoad Optimization By Steam And Blade Washing In A Flash Type Power Plant-A Case Study Of Olkaria Ii Geothermal Power Plant
http://repository.dkut.ac.ke:8080/xmlui/handle/123456789/4620
Load Optimization By Steam And Blade Washing In A Flash Type Power Plant-A Case Study Of Olkaria Ii Geothermal Power Plant
Cheruiyot, Bonface Kipkorir
Generator load is the key focus of a power plant which is significantly affected by its generating equipment which can be determined by both maintenance and the running parameters. The pa-rameters of interest for this study were turbine inlet pressure, steam flow rate, steam chest pres-sure (Bowl pressure) and Generator Loading. The operation of Olkaria II power plant was started in the year 2002, with Unit I turbine taking steam at a flow rate of 62.5 Kg/Sec (225 ton/hr). Af-ter operating for 2 years, steam chest pressure increased from 2.5 bar g to 4.1 bar g and steam consumption increased to 72.2 kg/s (260 T/hr.) with the turbine power generation capacity de-creased to 26.4 MW out of the rated capacity of 35.0 MW. After dismantling and inspecting for the purpose of this study in 2015 the turbine and its major auxiliary equipment, it was found that significant Sulphur deposition, scaling and related compounds had occurred on the turbine shroud, the turbine nozzles and the cooling tower, reducing their efficiency and leading to re-duced power generation. The purpose of this research was to explore blade washing and steam washing operation procedures for removal of silica scaling and deposition at the Turbine blades and nozzles, improving the geothermal power plant efficiency through addressing scales and mineral deposition for improvement of plant performance and productivity. The method em-ployed was the use of steam and blade washing technique. Condensate water is tapped and pumped through spray nozzles to the main steam line while in operation mode (power genera-tion).The pump discharge pressure to the main steam line is 14 bar g and this is above the main steam line pressure of 4.2 bar g. This sprayed water atomizes and increases the density of the steam in the localized area of the main steam line. This mixture then hits the silica deposits around the Turbine blades and nozzles and over a period of time the silica scaling is washed away under pressure. In real time data analysis, the study realized that steam and blade washing have positive effects on load optimization. Once the turbine blade washing was introduced, the steam flow rate needed to generate 1Mwe of power was reduced from a high of 7.9Kg/s to a mean value of 7.24Kg/s. This therefore makes this study conclude that blade washing and steam washing programs improves on turbine efficiency hence optimizes load in a geothermal power plant from silica dominated systems. The research analysis therefore enhances the study of the effects of steam and blade washing on the silica scaling, steam chest pressure, and power plant efficiency.
2019-03-01T00:00:00ZA Case Study Of Three-Dimensional Inversions Of Electrical Resistivity To Image Geothermal System In Korosi Geothermal Prospect-Kenya
http://repository.dkut.ac.ke:8080/xmlui/handle/123456789/4619
A Case Study Of Three-Dimensional Inversions Of Electrical Resistivity To Image Geothermal System In Korosi Geothermal Prospect-Kenya
Mathew, Muthuuri Arthur
In real situation the physical earth is in three Dimension (3D), a two dimension (2D) and one dimension (1D) earth models may not therefore explicitly explain or characterize the 3-D Earth in all situations. This is a simple and apparent reason why one needs a higher dimensional interpretation of Magnetotelluric (MT) resistivity data in modelling geothermal reservoirs. 2D MT interpretation is frequently applied in geothermal assessment and in many cases has effectively provided accurate information of geothermal reservoirs. Conversely, due to intricate geological environments, 2D interpretation sometimes fails to produce representative models, especially for deeper parts of reservoir. It is also the case in other natural resource assessment and geo-scientific research, such as oil exploration or underground water resources, volcanological studies etc. In this regard, 3D interpretation techniques are now in high demanded for understanding of true resistivity structures in various geological applications. This research describes (3D) MT inversion for 147 MT data sets obtained from Korosi geothermal prospect. The inversion scheme was based on the linearized least-squares method with smoothness regularization. Forward modelling was done by the finite difference method, and the sensitivity matrix was calculated using the adjoint equation method at each iteration. The research has helped to recover deeper resistivity structures in Korosi geothermal prospect. The results further infer two geothermal reservoirs below Korosi - Chepchuk massif. A close correlation between major surface structures, fumaroles, and the 3D model is observed. Consequently, the extent of geothermal resource at Korosi - Chepchok prospect, the depth of the inferred geothermal reservoirs. This research will in future assist in future prospecting of Korosi Geothermal area.
2018-03-01T00:00:00Z