Many offshore installations are dependent on power generated by gas turbines and a critical issue is that these experience performance deterioration over time. Performance deterioration causes reduced plant efficiency and power output as well as increased environmental emissions. It is therefore of highest importance to detect and control recoverable losses in order to reduce their effect. This thesis project was therefore initiated to evaluate parameters for detecting performance deterioration in addition to document different aspects of gas turbine degradation and performance recovery. Compressor fouling is the largest contributor to performance deterioration. Investigating fouling was therefore the main focus of this study.In the present study the deterioration rates of four different gas turbines were evaluated. When choosing gas turbines it was emphasised to select gas turbines operating under equal conditions but with different washing procedures. In addition to offline washing two of the gas turbines had daily online washing routines and one of the gas turbines run idle wash every 1000 hour between each offline wash. Data was extracted from the monitoring software, TurboWatch, and loaded into Excel files. MATLAB scripts were created to handle the large amount of data and visualize performance trends. Series of two parameters were plotted against each other and the graphs were evaluated.The evaluation showed that an overall trend was that the gas turbine that had been running with online washing continuously over a long period of time had higher performance than the reference engine. For the second gas turbine a daily online washing procedure has recently started. The advantage with the evaluation of this gas turbine was that a good reference engine was available. The two engines were operating under quite similar conditions at the same location in addition to having equal filter systems. Some deterioration trends were possible to detect. For the first period both engines seemed to have quite equal deterioration trends. During the second period no clear trends were seen in corrected CDP and corrected EGT when evaluated for constant GG speed. The compressor efficiency had decreasing trends for both engines during the second period as well, but the compressor efficiency for machine 1 was overall higher during the period with online washing than the previous period. The borescope pictures taken after the first period with online washing showed good visual results. However, it is too premature to make a final decision regarding the exact performance gain of online washing. At the time the study was performed the engine had only been running online washing for one operating interval, and more investigation over longer time is recommended. For the engine running with idle wash it was not possible to conclude on the basis of the collected data. No clear deterioration trends were detected and investigations over longer time and several operating intervals are recommended. It is also important to be aware of the fact that the performance gain of idle wash needs to be much higher than for online washing in order for idle wash to be economically profitable. There are several uncertainties related to performance trends. These include inaccuracy in instrumentation, monitoring software, calibration etc. Due to the fact that all the gas turbines evaluated in this study only have standard instrumentation it caused additional uncertainty in the performance trends. One suggestion for further study is to initiate a test instrumented gas turbine into operation with sensors for measuring inlet pressure depression

Increased knowledge of the degassing process in separation of gas from oil is important in connection with development of subsea separation and boosting units for heavy oil fields. The focus in the thesis is on theory and equipment design for two-phase separation of oil and gas. A review of gravitational separators and compact separation technology with a focus on subsea installations is given first. An extensive literature review related to theory governing the degassing process is further presented. The effectiveness of the degassing process depends on the gas’ ability to migrate out of the oil. Bubble dynamics theory, especially correlations for calculation of a bubbles velocity in a liquid is therefore examined. Bubble size, fluid properties, especially liquid viscosity, and gas volume fraction in the liquid is decisive factors for the bubble velocity. A comparison of several correlations obtained in various literature is made to determine the best available for modeling degassing. Most of the correlations have a limited range of validity in terms of bubble size and Reynolds number. It is verified that they are highly inaccurate outside this range. A correlation developed to be valid for a large range of bubble sizes seems to predict bubble velocities reasonably well. Because of its large range of validity, this is chosen to be used in the development of a separator model. Some experimental work is performed on two liquids with different viscosity. It is verified that separation of gas in viscous liquids requires significantly more retention time for the smallest bubbles reach the liquid surface. Occasional deviations from the examined theory are observed, especially for the more viscous liquid. Based the chosen correlation for bubble velocity a simplified model for horizontal and vertical gravity separators is developed. Separator size, fluid properties, flow rate and distribution of bubbles are input parameters. The model calculates how much of the initial gas volume fraction that remains in the liquid after separation. Consequence of high liquid viscosity and distribution of bubble size and bubble distribution in the liquid are evaluated by use of the model. When the oil becomes very viscous is it important that separator and internals are designed to optimize the conditions for degassing. This implies among others an inlet device which provides an ability to control the bubble distribution and keep the size of bubbles as large as possible. Methods are suggested for increased effectiveness in degassing of heavy oils, by reducing viscosity, increase the coalescence rate and affecting the flow pattern. Separation of other phases and undesirable components is also important and may make it difficult to optimize the design for the degassing process. However, a separator should be efficient in all respects, making knowledge of the degassing process anyhow important. The thesis gives an overview of important parameters in the degassing process. Much work still remains to develop correlations and models which can give a more exact description of real systems. Continuous development in separator components and not at least compact separation technology is important to effectively be able to produce heavy oil, especially in terms of subsea installations.

Tatt for meg flere runder med forsøk og analyser. Tørking av muselever,-hjerte,-lunge,-nyre og -skjelett muskulatur ved +5ºC og -10ºC. Samt lagring ved +4ºC og -20ºC i fem måneder. Resultatene viste en sammenheng mellom lave temperaturer og høye verdier av RIN. De viste også en motsetning til tidligere resultater, med lavere RIN på prøver tørket ved +5ºC, samt uakseptable lave verdier ved lagring i kjøleskap. Dessuten var det en viss forskjell avhengig hvilket organ vi tørket og lagret.

Vannkraftlaboratoriet ønsker å bygge en testrigg for peltonturbiner som tilfredstiller kravene til IEC 60193. Den eksisterende riggen må oppgraderes og det må implementeres mulighet for måling av friksjonsmomentet. I denne oppgaven vil det designes, maskineres og installeres ny lagerbukk med mulighet for friksjonmåling. IEC 60193 gjennomgåes med hovedvekt på laboratorieutrustning og måleusikkerhet for å se hvilke krav som må tilfredstilles. Et komplett hilldiagram kjøres før og etter oppgraderingen og det gjøres usikkerhetsanalyser på resultatene. Videre sammenlignes og analyseres virkningsgradkurvene med og uten friksjonsmoment.Oppgraderingen av Testriggen viser seg å være en suksess. Den gir gode stabile målinger og tilfredstiller IECs krav til usikkerhet. Den står nå klar til å gi nøyaktige målingeresultater for videre forskning på peltonturbiner.

The production of model Francis runner to be used in the Waterpower laboratory at NTNU is a length and costly process. Due to the production cost there are years between each time a new Francis model is bought. The Tokke Francis model at Waterpower laboratory, was given from the industry after they had run model tests in the laboratory when design- ing the Tokke prototype.In order to give the students at the Waterpower laboratory an opportunity to design their own turbines and test, the production cost must be significantly reduced. To be able to do that, new designs need to be developed and new production method used.The objective of this thesis is to carry out a new mechanical design of a Francis model runner and evaluate different mechanical designs of guide vanes and stay vanes. The new alternative designs were made with a combination of standard production methods and material, and new plastic materials from rapid prototyping such as selective laser sintering (SLS) and rapid CNC machining.To carry out the new mechanical runner design, the MATLAB design software Khoj was used. From Khoj two sets of streamlines were generated, one set for the sucction side and one for the pressure side. Then the streamlines were imported into the CAD program PTC Creo Parametric and a 3D-model of the design was made.Two test pieces in a polyamide material was made using selective laser sintering. One of the test pieces was tested for pull-out strength using some self tapping thread inserts, the results showed that the pull-out strength was more than good enough. The threaded insert could be used to attach the runner vanes to the hub and ring.The main focus of this thesis has been the new mechanical design of a model runner and runner vanes. The model design was not produced and tested in the laboratory due to lack of time and money.