“FIRST TIME RIGHT” DESIGN THROUGH EXPERTISE AND EXPERIENCE
As an engineering consultancy, Xeamos has built its own calculation models based on theoretical calculations, intensive lab testing, and monitoring its installed base. We apply special CFD (Computational Fluid Dynamic) software to simulate and analyse fluid flow and thermal behaviour in technical processes. We also check all new system configurations on mechanical strength, vibration (“eigenfrequencies”) and acoustical performance. And as we, and our customers, don’t like unpleasant surprises, we know that a new system will meet its required performance, even before delivery and commissioning.
To design a well-performing exhaust after-treatment system a few factors have to be taken into account. To give you an idea about the complexity, here are just a few:
- Back pressure: The total back pressure must stay within the certification limits of the engine. The CFD picture above shows the flow lines and pressure in an In-line MPAT DPF+SCR after-treatment system.
- Temperature uniformity during active regeneration: To prevent damage or premature wear hot spots on steel work, diesel particle filters, catalyst modules must stay within limits.
- Flow uniformity across the catalyst modules: an uneven distribution leads to a poor performance of the system.
- Urea distribution: A thorough mixing and distribution of urea is essential to achieve the required emission reduction and prevent ammonia slip.
- Mechanical strength: The reactor housing must withstand high temperatures, pressures and vibrations. We also take fatigue effects due to exhaust pulsations into account.
- Excessive vibration of steel parts due to the fact that the ignition frequency of the engine is close to the “natural frequency” or “eigenfrequency” of certain parts of the reactor housing. If critical, we check the natural frequencies of the reactor housing with special software tools.
- Acoustic aspects: With our calculation model we calculate the sound attenuation of the system. Specific dimensions of the reactor housing are designed in such a way that the ignition frequencies and harmonics are sufficiently supressed.
- Heat transfer and thermal insulation: The heat of the exhaust gases has to stay inside in the system.