Long-term Operational Experience Research Articles

The cosmic-ray experiment KASCADE

KASCADE has been designed to measure air showers of primary cosmic-ray energies in the PeV region and to investigate the knee phenomenon in the all-particle energy spectrum. Several observations are measured simultaneously for each event by different detector systems. The experiment started to take data in 1996 and has been completed and extended since then. The individual detector systems and their performances are described. Also, the experience in long-term operation of the experiment and the interplay between different components is outlined.

Long-term operational experience with first siemens 400 kW HTS machine in diverse configurations

Siemens has built a synchronous machine consisting of an HTS rotor and an air-cored stator. Rotor cooling is provided by a Gifford-McMahon (GM) off the shelf cryocooler, the typical requirement being about 30 W @ 25 K. The machine was designed for a rated power of 380 kW (rated voltage 3 phases 400 V Y), but achieved a maximum continuous power of 450 kW and a short term maximum power of 590 kW at 1500 rpm. In all cases, output power was limited by stator cooling. Characteristic parameters such as reactances, inductances, and time constants were determined to obtain a consistent overview of the machine properties. The machine was tested under different operational modes, including motor mode as well as generator mode. In the generator mode, it was operated on water cooled resistors or connected to the grid. The properties of motor mode have been determined synchronized to the grid as well as via an inverter. Special attention was taken to investigate the influences of asymmetric loads, grid and inverter harmonics on rotor cooling requirements. Numerical calculations were performed and compared to the experimental data showing good correlation.

Heat transfer and fouling behaviour of Siemens PWR steam generators – long-term operating experience

The evolution of heat transfer performance of the steam generators (SGs) is regularly monitored on the basis of plant data recordings in many Siemens pressurized water reactors (PWRs). For the oldest SGs operating experience covers more than 27 years. Heat transfer performance is quantified in terms of the fouling factor. It is correlated with the amount of iron ingress into the steam generator stemming from the feedwater/steam cycle. After all plants that have started under phosphate treatment have converted their feedwater chemistry to H-AVT treatment (all volatile treatment with hydrazine dosing to assure high pH-values), iron transport in these plants has drastically reduced and, consequently, the fouling increase has almost stopped. In plants which operate under H-AVT from the beginning, no significant fouling factor increase has been observed after up to 15 years of operation. Hence, H-AVT is the preferred feedwater chemistry treatment – not only from a corrosion prevention point of view but also from a heat transfer performance point of view. The thermal effects of chemical cleaning as well as the fouling behaviour specific to economizer-type SGs are also addressed in this paper.

Technical Features and Long-term Operating Experience of Mitsubishi Advanced M 501 G Gas Turbine

The combined cycle power plant is recognized as one of the best thermal power plants for its high efficiency and cleanliness. Under these circumstances. Mitsubishi Heavy Industries, Ltd.(MHI) developed large, heavy-duty 1, 200C class M 701 D (for 50Hz utility) gas turbine and 1, 400C class M 501 F (for 60Hz)/M 701 F (for 50Hz) gas turbines. Their high efficiency and reliability for combined cycle applications have been proven in field operations. Based on the fact that the combined cycle efficiency is highly dependent on the gas firing temperature, MHI has newly developed the 1, 500C class M 501 G (for 60Hz)/M 701 G (for 50Hz), which is called “G” series, gas turbines.Development of the “G” series gas turbine was started in early 1990' s and the design was based on the following concepts, which give excellent performance and high reliability to the “G” series.Firstly, proven features from the “F” series are kept. Secondly, the most advanced technologies in aerodynamic design, heat transfer design and new materials for the “G” series are introduced. Thirdly, our conventional design criteria in industrial gas turbines are applied. Fourthly, NOx and the metal temperature remains at the same level as the “F” series by applying steam-cooled combustors even though the turbine inlet temperature is increased. Finally, special measurements and verification tests are carried out before commercial operation to secure their high reliability.The trial operation of the M 501 G was conducted in 1997 in the combined cycle verification plant in MHI Takasago. Japan. It was successful and the commercial operation was started in June 1997. Since then, the detail inspections were conducted and the condition of each component was quite sound. Therefore, the availability. defined as the actual power supply hours over demanded power supply hours excluding scheduled shutdown such as periodical inspection, during the commercial operation was 98.6%.The trial operation of the M 701 G was conducted in October 1998 in the domestic utility company. After completion of plant tests, the commercial operation was started in July 1999. The availability during commercial operation is 100%.This paper describes the technical features and up-to-date operating status of the M 501 G combined cycle power plant in MHI Takasago.

Long-term operational experience with the barrel CRID at SLD

The Barrel CRID detector has been operating successfully at SLD for the past seven years. It is an important tool for SLD physics analyses. The long-term operational experience with this device is described.

The performance of the Barrel CRID at the SLD; long-term operational experience

The Barrel CRID detector has been operating successfully at SLD for the past seven years. It is an important tool for SLD physics analyses. We report results based on long term operational experience of a number of important quantities such as the Cherenkov quality factor, N/sub 0/ of the device, fluid transparency, electron lifetime, single electron detection efficiency, anode wire ageing, TMAE purity, long term transparency, Cherenkov angle resolution and the number of photoelectrons observed per ring.

96/00226 Coal gasification and the power production market

The US electric power production market is experiencing significant changes sparking interest in the current and future alternatives for power production. Coal gasification technology is being marketed to satisfy the needs of the volatile power production industry. Coal gasification is a promising power production process in which solid coal is burned to produce a synthesis gas (syn gas). The syn gas may be used to fuel combustion integrated into a facility producing electric power. Advantages of this technology include efficient power production, low flue gas emissions, flexible fuel utilization, broad capability for facility integration, useful process byproducts, and decreased waste disposal. The primary disadvantages are relatively high capital costs and lack of proven long-term operating experience. Developers of coal gasification intend to improve on these disadvantages and lop a strong position in the power generation market. This paper is a marketing analysis of the partial oxidation coal gasification processes emerging in the US in response to the market factors of the power production industry. A brief history of these processes is presented, including the results of recent projects exploring the feasibility of integrated gasification combined cycle (IGCC) as a power production alternative. The current power generation market factors are discussed,more » and the status of current projects is presented including projected performance.« less

Experience in operating earth dams of the Niva cascade of the Kola regional power administration constructed in 1930?1960

1. As shown by the experience of long-term operation of earth structures of the cascade, on dams (embankments) being constructed by the method of dumping soil into water, when designing the slopes of these structures it is necessary to impose more stringent requirements with respect to determining the steepness of these slopes to increase their reliability, as is done for structures constructed dry. 2. To organize successful monitoring of seepage processes in the investigated structures having substantial anisotropy of the soil, special recommendations on the efficient disposition of piezometers under such specific conditions should be worked out. Recommendations on the disposition of piezometers under conditions of a noticeable effect of the groundwater regime of the surrounding territory on the seepage regime of the hydro development should be worked out accordingly. 3. Since the calculations made in the work, as a result of which instability of many slopes was detected, are not always confirmed by practice (there are examples of failure-free operation of slopes whose stability factors are considerably less than unity), it is advisable to correct the method of such calculations with consideration of the characteristics of the formation of the seepage flow in the downstream shoulder of dams with pronounced anisotropy of the soil.

Liquor heat treatment and high-dry-solids firing

In recent years, the main focus of the recovery-boiler development has been on the combustion-process technology. As the boiler capacity has increased, more and more emphasis has to be laid on the control of the furnace operations, for example, development of the air system. On the other hand, the increased environmental pressures have forced the suppliers to look for new solutions to reduce emissions radically, especially sulphur. Emissions have been reduced by cleaning the flue gases, but also by optimizing the combustion process. For several years, an increase of black-liquor high-dry solids has been a well-known technology to reduce SO 2 content in the flue gases. This paper discusses a liquor-heat-treatment process developed by A. Ahlstrom Corporation, and also the evaporation and combustion of LHT liquor in the light of the results gained from mill-scale tests and long-term operational experience.

Field Demonstration of the Linde Oxygen Combustion System on the EPA Mobile Incinerator

This paper summarizes the various system performance tests and the long-term operating experience of the LINDE Oxygen Combustion System installed on the US Environmental Protection Agency's Mobile Incineration System (MIS) when it was in operation at the Denney Farm site in southwestern Missouri. The LINDE OCS was installed on the MIS as part of a major modification program in 1987. The modified system was first demonstrated for three months in 1987 when various system performance tests were conducted. Test burns of the modified MIS showed destruction and removal efficiencies (DRE) surpassing both Resource Conservation and Recovery Act (RCRA) and Toxic Substances February 1988 to continue the incineration of dioxin-contaminated materials from sites in southwestern Missouri. After implementation of the modifications, over ten million pounds of dioxin-contaminated material including soil, lagoon sludge, plastics, trash, protective clothing, wood, etc., were processed. MIS operations at Denney Farm ceased in April 1989.

Long-term operational experience and upgrade of the cryogenic system for the superconducting cavities in the CERN SPS accelerator

Cryogenics at liquid helium temperature has been requested in the SPS for testing and operating superconducting accelerating RF cavities: in 1988 and 1989 a single LEP prototype cavity made of bulk niobium, in 1990 two cavities made of niobium sputtered copper and finally, in 1991, a single niobium sputtered cavity. To cope with the various cooling needs, we used the same refrigerator (120 watt at 4.5 K) and the associated cryosystem has been optimized to reduce the thermal load. The original transfer line has been replaced by a flexible and thermally shielded one made of six coaxial bellows. The achieved thermal performance for the various combination of superconducting cavities, the long-term behaviour and operational experience of the cryosystem are given. While the first cryosystem is maintained in operation, a new one (using a refrigerator of 400 watt at 4.5 K) is now being tested to increase, in 1992, the SPS accelerating field by means of two additional superconducting cavities. A description and the preliminary results of the new cryogenic facility are presented.

Techniques for and Experience with Biological Nutrient Removal – Danish Long-Term Operating and Optimization Experience

New Danish legislation demands that, by 1993, all wastewater treatment plants serving more than 15,000 PE must reduce total nitrogen and total phosphorus to 8 mg/l and 1.5 mg/l, respectively. On the basis of full-scale experience from more than 35 existing plants with nitrogen removal and 5 plants with biological phosphorus removal, these targets seem quite realistic. The plants are operated in accordance with the Danish-developed methods BIO-DENITRO (N removal) and BIO-DENIPHO (N and P removal). These-methods offer most of the advantages of both the Sequencing Batch Reactor and the recirculation systems but eliminate some of the disadvantages such as intermittent operation and discharge, and internal recirculation. Further developments towards improved process performance and control are achieved through the development of new plant types utilizing hydrolyzed sludge as an additional carbon source and through the application of mathematical models for simulation of the biological processes under various operating and load conditions.