Vattenfall

About: Vattenfall is a company organization based out in Stockholm, Sweden. It is known for research contribution in the topics: Wind power & Combustion. The organization has 685 authors who have published 857 publications receiving 18912 citations. The organization is also known as: Vattenfall AB & Kungliga Vattenfallstyrelsen.

Method and system for gas measurements in a combustion chamber

Abstract: The present invention relates to a method for determining at least one gas condition at a location in a combustion chamber of a power plant or a combined heat and power plant by means of a laser pulse. The method comprises emitting (S1) the laser pulse into the chamber, determining (S2) a first point of time at which the laser pulse is emitted into the chamber, detecting (S3) laser light backscattered by gas molecules at the location in the chamber, determining (S4) a second point of time at which the laser light backscattered by the gas molecules is detected, determining (S5) the location based on the first point of time, the second point of time, and a pulse length of the laser pulse, and determining (S5) the at least one gas condition at the location based on at least one characteristic of the backscattered laser light detected at the second point of time. A gas measurement system and a combustion system are also presented herein.

High temperature corrosion investigation in an oxyfuel combustion test rig

Abstract: Oxyfuel firing and subsequent capture of CO2 is a way to reduce CO2 emissions from coal-fired boilers. Literature is summarized highlighting results which may contribute to understanding of the corrosion processes in an oxyfuel boiler. Tests were conducted in a 500 kWth oxyfuel test facility constructed by Brandenburg Technical University to gain understanding into oxyfuel firing. Two air-cooled corrosion probes were exposed in this oxyfuel combustion chamber where the fuel was lignite. Gas composition was measured at the location of testing. Various alloys from a Cr steel, austenitic steels to nickel alloys were exposed at set metal temperatures of 570 and 630 °C for 287 h. The specimens were investigated using light optical and scanning electron microscopy and X-ray diffraction. The deposit on the probe contained predominantly CaSO4 and Fe2O3. Oxide thickness and depth of the precipitated (perhaps carburized) zone was used as a measure of corrosion rates. The lowest alloyed steel had the highest corrosion rate, and the other austenitic and nickel alloys had much lower corrosion rates. Precipitates in the alloy adjacent the corrosion front were revealed for both Sanicro 28 and C-276. However, it was observed that precipitates were present on both the concave and fireside convex tube surfaces, thus oxyfuel conditions cannot be responsible for these precipitations.

High resolution electron microscopy study on oxide films formed on nickel-base Alloys X-750, 182 and 82 in simulated high flow velocity BWR water conditions

Abstract: This work contributes to characterization of the oxide films formed on nickel-base alloys (Alloy X-750, Alloy 82 and Alloy 182) under simulated BWR water environments at ~10 or 18 m/s with or without iron injection. HR SEM/TEM and FIB techniques were applied. The oxide thicknesses on different alloys were substantially different, ranging from 50 nm to 8 μm. For Alloy X-750 and Alloy 182 exposed without iron injection, similar oxide phase compositions consisting of sub-micron Fe2O3 and NiFe2O4 grains as well as NiO were formed but with substantially different microstructures. For the corroded Alloy X-750 there was an additional dense layer of possibly Ni1.5Cr0.5O3 in between the NiFe2O4 and NiO layers. On Alloy 82 which contained a relatively low Fe-content only a thin but dense film of Cr1.3Fe0.7O3 was seen. With iron injection the oxide films formed on Alloy 82 were similar to that on the Alloy 182 without iron injection, suggesting that iron injection may play a similar role as if the alloy had an elevated iron content. The implication of the observations for material corrosion behavior in BWRs is elaborated.