Showing papers by "Vattenfall published in 2003"
TL;DR: A concentrating photovoltaic wall element, including Cu(In, Ga)Se-2-based modules, aluminum reflectors, and an insulation for building integration, has been developed and evaluated.
53 citations
Patent•
23 Jun 2003TL;DR: In this paper, a process for separating, concentrating and recovery of boron compound from aqueous solution containing bors, strongly dissociated anions and some cations is described.
Abstract: A process is provided for separating, concentrating and recovery of boron compound from aqueous solution containing boron, strongly dissociated anions and some cations. The process specifically integrates electrodialysis with ion exchange to selectively separate boron from aqueous solution that contains a wide concentration range of boron, strongly ionised anions such as chloride, nitrate and sulfate, and cations like lithium. The process is adapted for controlling boron concentration in an industrial process, for the recovery or purification of boron and some cations like lithium form aqueous solutions, and for wastewater treatment.
35 citations
TL;DR: In conclusion, cleaning flue gases in two or three stages reduced Hg emissions well below Swedish regulations, demonstrating the decreasing use of Hg in society the last two decades as influenced by governmental policy regarding Hg.
20 citations
TL;DR: In this paper, a utility eye-view of the European power sector's CO2-compliance decision process under a tradable emissions scheme is provided, which indicates that, in the medium term, many utilities are likely to consider options based on traditional power technologies such as converting existing coal-fired capacity to burn gas, extending the lives of nuclear capacity, and replacing old coalfired plants with more efficient gas- or even coalfired units.
13 citations
TL;DR: In this article, the simulated effect of large windfarms on the frequency of the interconnected grid system within which they are operating is modelled on Germany and the results reveal that the stochastic nature of wind power at significant capacity may cause noticeable frequency fluctuation on the whole grid.
Abstract: The paper describes the simulated effect of large windfarms on the frequency of the interconnected grid system within which they are operating. The study is modelled on Germany. The features of the well-tested and widely used power system simulation package Power System Dynamics (PSD) were expanded so that windfarms with all commonly used wind turbine generators and their control structures can be simulated. In particular, the windfarm interaction with the power grid can be studied. Additionally, the effects of topology and wind conditions at the location of the wind turbines on the output power have been incorporated into the simulation. The result reveals that the stochastic nature of wind power at significant capacity may cause noticeable frequency fluctuation on the whole grid. Without countermeasures, the fluctuating power may use a disproportionately large component of the primary control power reserve of the grid system. The paper describes options for the integration of large offshore and onshore ...
12 citations
TL;DR: A new method for eigenvalue prediction of critical inter-area stability modes of the European electric power system based on Neural Networks (NN) that can be predicted very fast and with high accuracy.
10 citations
TL;DR: In this article, a chemical gas sensor based on a silicon carbide field effect transistor with a catalytic gate metal has been developed for a number of years, and the selectivity of the sensor devices is established through the choice of type and structure of the gate metal as well as the operation temperature.
Abstract: A chemical gas sensor based on a silicon carbide field effect transistor with a catalytic gate metal has been under development for a number of years. The choice of silicon carbide as the semiconductor material allows the sensor to operate at high temperatures, for more than 6 months in flue gases at 300degreesC and for at least three days at 700degreesC. The chemical inertness of silicon carbide and a buried gate design makes it a suitable sensor technology for applications in corrosive environments such as exhaust gases and flue gases from boilers. The selectivity of the sensor devices is established through the choice of type and structure of the gate metal as well as the operation temperature. In this way NH3 sensors with low cross sensitivity to NOx have been demonstrated as potential sensors for control of selective catalytic reduction (SCR) of NOx by urea injection into diesel exhausts. Here we show that sensors with a porous platinum or iridium gate show different temperature ranges for NH3 detection. The hardness of the silicon carbide makes it for example more resistant to water splash at cold start of a petrol engine than existing technologies, and a sensor which can control the air to fuel ratio, before the exhaust gases are heated, has been demonstrated. Silicon carbide sensors are also tested in flue gases from boilers. Efficient regulation of the combustion in a boiler will decrease fuel consumption and reduce emissions.
9 citations
Patent•
28 Nov 2003TL;DR: In this paper, a gas-tight heat exchanger is used for preheating the oxygen, e.g., a plate- or pipe-based heat exchamer. But this is not the case in this paper, since it is assumed that the oxygen used in combustion of the fossil fuels is preheated by being used to cool the waste gas.
Abstract: The oxygen used in the combustion of the fossil fuels is preheated by being used to cool the waste gas. The quantity of recirculated waste gas is increased. A gas-tight heat exchanger is used for preheating the oxygen, e.g. a plate- or pipe-based heat exchanger.
6 citations
TL;DR: In this article, the authors investigated the potential usefulness of TOF-SIMS for chemical analysis of deposits formed in combustion reactors and found that the main components in the deposit samples were KCl and K 2 SO 4, while K 2 CO 3, NaCl, Na 2 SO4, Ca(OH) 2 and CaCl 2 were present in smaller concentrations.
6 citations
Patent•
23 Jan 2003TL;DR: In this paper, a heating surface of a steam generator comprising a multitude of approximately parallel heating tubes through which a cooling agent passes is represented by protective sleeves which rest loosely on the surface of the heating surface tubes between the mountings thereof.
Abstract: The invention relates to a heating surface of a steam generator comprising a multitude of approximately parallel heating tubes through which a cooling agent passes. Said heating tubes are arranged in the flow channel of the steam generator by means of mountings. The aim of the invention is to embody the heating surfaces of the steam generator in such a way as to prevent the continuous build-up of deposits in the form of slagging, and the disadvantages associated therewith, in the area through which the flue gases pass. To achieve this, the heating surface tubes are surrounded by protective sleeves which rest loosely on the surface of the heating surface tubes between the mountings thereof. The ends of the protective sleeves exhibit an expansion distance to the mountings of the heating surface tubes. The heat expansion coefficient of the material forming the protective sleeves is higher than that of the material forming the heating surface tubes.
4 citations
Patent•
28 Nov 2003TL;DR: In this paper, the power generation blocks are operated in a modified pressure operating mode, with the turbine inlet valves throttled and a pure pressure-operating mode, and the turbines inlet inlet valve fully open.
Abstract: The regulation method has the power generation blocks operated in a modified pressure operating mode, with the turbine inlet valves throttled and a pure pressure operating mode, with the turbine inlet valves fully open. Several power generation blocks are activated for elimination of quasi-stationary frequency deviations of +/- 200 MHz, with quasi-stationary frequency deviations of +/- 40 MHz eliminated by throttling the turbine inlet valves, the quasi-stationary frequency deviations between +/- 40 and +/- 200 MHz eliminated by operation of the power generation blocks in a pure pressure operating mode.
TL;DR: In this paper, an advanced secondary control concept (tie line bias control) is introduced for a fair splitting up of the whole renewable power generation, which is fed into the interconnected power system, to the different grid partners.
Patent•
24 Apr 2003TL;DR: In this article, an Independent claim is also included for a device for preventing off-track running of a filter cloth in a vacuum band filter press comprising a monitoring device in the form of a reflex light scanner for the outer edge of the filter cloth.
Abstract: Process for preventing off-track running of a filter cloth in a vacuum band filter press comprises uniformly guiding the cloth on one side over a rotating roller; and lifting the outer edge of the filter cloth in a tightened manner. An Independent claim is also included for a device for preventing off-track running of a filter cloth in a vacuum band filter press comprising a monitoring device (1) in the form of a reflex light scanner (2) for the outer edge (4) of the filter cloth (3). A clamp (6) with a bolt (7) and a rotating roller (8) is arranged in the circulation of the filter cloth at a distance of 0.20-0.80 meters from the monitoring device on a support (5) of the vacuum band filter press.
Patent•
27 Nov 2003TL;DR: In this paper, the bulk material is transported in an inclined transport channel consisting of an upper box for transporting ash and a lower box for feeding air with an intervening layer of air transmissive material.
Abstract: The bulk material is transported in an inclined transport channel (1) consisting of an upper box (2) for transporting ash and a lower box (3) for feeding air with an intervening layer of air transmissive material (4). One or more cascaded collecting plates (5) with an opening against the transport direction (9) is or are arranged on the air transmissive material layer over its entire width. Each plate opens into a common vertical drop shaft (6) and is connected to an ash silo via a pneumatic pressure vessel conveyor.