Before talking about the present usage, an understanding of the DELTA WING® technology should be facilitated by means of a brief introduction to how it works. The name DELTA WING® comes from the world of aeronautics, where the leading-edge vortices of all delta airplane wings are well known. These vortices differ from the otherwise familiar Kármán vortices that arise as a result of flow separation around spherical bodies in a gaseous or liquid flow. The oscillation of the resulting vortex field is a typical characteristic of these. In contrast, leading-edge vortices do not oscillate; instead, they retain their geometric form and position in space (see Fig. 1.).
Thus, each plate generates its defined amplitudes and geometrically stable vortices once exposed to a flow (see Fig. 2). Operation is load-independent and the resulting flow field is stable. As well as meaning that no readjustments are required later on, this means that the engineer can generate a predictable flow field. While numeric methods are increasingly gaining ground, it is important to note that – at least at present – CFD methods are insufficient, and all tests need to be carried out on physical models.
The phenomenon of leading-edge vortices described above was already applied in a world first for the industrial sector and power plant segment more than 35 years ago by Balcke-Dürr. Since then, intelligent mixing and flow guidance solutions have been developed for the holistic control of flow systems, bringing about a results quality that is without competition. These solutions are based on our models, which have been ideally formulated for this purpose, and the observance of all similarity conditions necessary for the modeling process.
The Rothemühle DELTA WING® technology is a reliable, low-maintenance solution for numerous applications in industry and the energy supply sector. For decades, BDRM has been developing mixing and flow guidance systems that consider the flow system as a whole. Of numerous applications, the practically perfect inflow results of SCR catalytic converters and ESPs should be mentioned, despite their extremely challenging complexity. In addition, DELTA WING® technology is ideal for the dispersion of bulk goods, particularly for dry sorption. Our mixer plates can optimally mix even high-dust gas flows and direct them through the channelling system to an SCR catalytic converter or ESP. In both cases, problematic inflow conditions are mastered elegantly, avoiding undesirable behavior such as flow separation, return flow, blockages, deposits, and load-dependent flow unbalances. This results in a predictable balanced or shaped inflow field across the entire profile. Special attention must be paid to the particulate matter in the flow. Usually, operators are concerned with dust deposits and erosion on the plates, supporting structures, and channels. Thanks to the tangential flow on the plate surface, the surface remains free from deposits due to the vortex field and the principles involved. The channels, too, are largely free from dust deposits, as can be seen in Fig. 4.
The shape of the plates and our specially designed and positioned support structure offer no room for erosive attacks. See Fig. 5.
DELTA WING® plates in the inlet hood of an ESP in a new power plant
DELTA WING® mixer in a German deSOx plant after around 15 years of operation. The inner walls and walls of the channels are free from dust deposits.
Design details of a DELTA WING® plate field in a pre-mounted gas channel
Even though the DELTA WING® plates are designed as additional inner fittings, the extra pressure loss is extremely small and often almost imperceptible. This is partly because the plates are simply flat surfaces with a setting angle, and such plates naturally cause only a small pressure drop. In comparison with traditional solutions that force the liquid flow in the desired direction by means of inhibiting structures, the pressure loss is generally 5 to 10 times less. Furthermore, the positioning of the plates can be used to largely avoid any separation of the flow from the walls, which is generally a main contributor to pressure losses, particularly in the case of difficult geometries such as diffusers like ESP hoods. The end result is a reliable, stable, tailored solution based on more than 30-years of experience in a whole range of applications.