With the VGB-Newsletter January/February 2012 you had been informed on the a.m. consultation process. Due to the complexity of the presented draft VGB decided to extend the consultation procedure until April 30, 2012, 24:00 h.
In the time between 6 and 10 of February 2012 a VGB delegation has visited Japan in continuing the successful cooperation between TENPES and VGB Members. The meeting was focussed on:
* Impact of Tsunami;
* Energy Policy Japan;
* Technology Aspects.
In this project the drop-wall or drop-wall liquid layer interaction and the liquid layer redispersion on internal installations have been studied. First, the basic phenomena of the droplet-wall interaction have been characterized and a classification of this application case was carried out. Subsequently, theoretical models gained from literature were assessed. It has been determined that none of the models describe the drop-wall interaction in a FGD scrubber totally adequate. As a consequence, a test rig has been designed to establish a new drop-wall liquid layer interaction model allowing CFD simulation of FGD scrubbers. Relevant parameters of the separation model are the properties of the liquid viscosity and density, velocity and incident angle of the drops, and the speed and height of the wall liquid layer. By comparing different spray level configurations the knowledge has been gained that the wall liquid layer is primarily impacted by the direct spraying of the nozzles and that the adjusted flow has only little effect on the separated mass and thus the resulting wall liquid layer. If luidic fittings are used to displace and redisperse the wall liquid layer, the influence of the redispersion on the flue gas flow exceeds the purely geometrical effect of a chicane in the form of an annular flow cross-section reduction.
More information and final report:
The combustion of coal and the co-combustion of waste in power plants mobilize mercury (Hg) from the fuels with the flue gases. A part of the mercury is bound to particles and can be separated in the dust separation equipment. The downstream FGD scrubber is the major sink for the oxidized mercury species in the flue gas. In contrast to other salts mercury halides initially does not exist dissociated in aqueous solution and have thus like all physically dissolved substances a noticeable vapor pressure. Dissolved Hg (II) can also be reduced under certain process conditions to largely water-insoluble elemental Hg (0), which leads to a re-emission of Hg in the clean gas. By addition of additives to the FGD process, the Hg (II) species can be transferred into dissociated complexes and poorly soluble compounds or can be adsorbed on solid surfaces, whereby the vapor pressure and the re-emission are reduced. Against this background, in laboratory experiments, the effect of different adsorption, precipitation and complexing agents on the mercury vapor pressure above the FGD suspension and the dissolved mercury were studied. After studies on model suspensions, effective additives were tested on various technical suspensions of lignite and hard coal firing FGDs. Significant reductions in mercury emissions could be detected - with simultaneous reduction of the dissolved mercury concentration - by means of selected activated carbons and mineral adsorbents in model as well as in technical suspensions. Due to the density difference to the gypsum it may be possible to separate both in the hydro cyclone. Also several sulfur-containing organic and inorganic precipitants (Epofloc L1R, TMT, Nalco 8702, Pravo) were successful tested. When using this precipitants the redox potential of the suspension is about 100 mV reduced. With complexation (e.g. using bromide or cyanides) the mercury remains dissolved in the suspension. An increased entry of mercury in the FGD gypsum phase does not occur. However, in industrial suspensions - even with a clearly increased consumption of additives - a much lower mercury reduction was observed.
More information and final report:
Within this research project, it is demonstrated by validation that the flue gas flow calculation formulas from EN 12952-15 perform very well for a wide range of fuels. The EN 12952-15 standard is a suitable international reference for flue gas calculation. There are important requirements for reporting the mass emissions from combustion installations and it is important that calculation methods are underpinned by reference to international standards. The performance of the calculation methods is quantified and, in many cases, the calculation approach is superior to instrumental measurements. The authors therefore recommend the use of calculation methods as a cheap, accurate and relatively simple means of determining flue gas flow rate.
The report is available at:
The best available technique in the high temperature-fine particle separation is defined by ceramic filters. These have application limits of about 800 to 900 degrees Celsius. For high-temperature processes such separation technique is not yet realized on industrial scale. From previous examinations the knowledge was gained that above temperatures of about 800 degrees Celsius the electron emission from ceramic system components dominates the charging behaviour of the particles, so that an effective charging of the particles and thus a separation possibility by electrostatic effects are already given in this temperature range. This method in principle is interesting for other high temperature processes. The aim of this project was to develop a fine particle separator allowing a nearly isothermal separation of fine particles at temperatures above 800 degrees Celsius using active and passive potential fields. The particle charge resulting from the thermal emission of particles and ceramic surfaces is used for separation in an electric field ("thermoionic ESP"). Various ceramics were tested in a pilot plant to optimize the particle separation. The newly developed thermionic electrostatic precipitator is suitable for a fine particle separation with pre-installed precipitation of coarse particles. The coarse particle precipitation has to meet the conditions of particle concentration and size. The process should be relatively insensitive to changes in the gas atmosphere where the gas properties vary only slightly.
More information and final report (available only in German):
Further information about VGB-R106e "Tubes for Condensers and other Heat Exchangers for the Operation of Steam Turbine Plants - Copper Alloys" can be viewed at the following link:
Further information about VGB-R113e "Tubes for Condensers and other Heat Exchangers for the Operation of Steam Turbine Plants - Stainless Steels" can be viewed at the following link:
Further information about VGB-R114e "Tubes for Condensers and other Heat Exchangers for the Operation of Steam Turbine Plants - Titanium" can be viewed at the following link:
Further information about VGB-R167e "Overhaul recommendations for turbo-generators" can be viewed at the following link:
Further information about VGB-M701e "Analysis of FGD Gypsum" can be viewed at the following link:
Main topics of the March issue are: Increase in flexibility with latest technologies; Comments on the ENTSO-E Network Code; The EPRTR and possible implications regarding coal-fired and natural gas-fired power stations; The revised VGB-Standard for water-steam-cycle chemistry.
Abstracts of all articles are available here: