Cement, Energy and Environment

• • t 4 Latest design of IKN coolers for reci rculation The IKN cooler consists of a fixed clinker inlet distributing system (KIDS 0 ), patented Coanda Wing® technology for horizontal aeration in transport direction, and wear- less pendulum suspension of the mobile system. Taking advantage of the Coanda effect, cooling air jets from narrow inclined slots are kept adjacent to the grate surface, forming an air cushion and then providing even aeration through the clinker bed. Coanda jets simulate an infinite number of openings on the grate surface which provide even air supply to the voidage and micro-channels within the packed bed, thus enabling the fines to be lifted to the bed surface for gentle fluidization. For many years and for more than 560 installations worldwide, this concept has been synonymous with low power consumption, high heat recuperation, proven availability and easy maintenance. The new design improves cleaning of the grate plates and optimizes air flow from below the cooler grate. When running the cooler in recirculation mode, cooling air is always extracted at the end of the cooler, but in many cases also from a separate mid-air offtake and is routed through a dedusting solution like a dust settling chamber or a cyclone. Before entering the recirculation duct, heat is extracted by a heat exchanger, which could be a boiler type, if a WHRS is in place, or an air-to-air straight-tube heat exchanger. Fans of the KIDS part (fixed inlet of the cooler) as well as fans of the central part of the cooler are fed by warm air coming from the order to be able to redirect the vent air to the cooler. The mobile grate of the Pendulum Cooler® by IKN is driven by a single or two synchronized hydraulic cylinders. The drive is located at the front end of the cooler, outside of the under-grate compartments, and can be accessed at any time. No lubrication under the grate is needed due to the patented LPS®supporting the mobile frame. 5.2 Fans To achieve compliance with the recirculation concept, special emphasis has to be placed on the cooler fans. They comply with higher temperatures and depending on the dedusting solution, higher dust loads as well. Thus preconditions for a certain wear protection of the fan have to be met. 5.3 Instrumentation Normal instrumentation of cooler fans includes inlet nozzles. Pressure sensors measure the inlet pressure at the ducts behind the fans. When fans are connected to the recirculation duct, a conventional inlet nozzle cannot be used and the fans have to be equipped with flow sensors. They are capable of measuring flow rates even at elevated temperatures. Since the flow in the duct is dependent on the respective temperature at different positions in the recirculation duct, temperature sensors have been installed. As a result, each air flow measurement corresponds to the respective temperature to ensure proper calculation of the real air flow in the duct. recirculation duct. On demand, warm .--- --- -------------------., air from the recirculation is mixed with Table 1 Thermal output of different systems with and without fresh air by means of a fresh air damper or by a separate fan fed with fresh air. The last fans in a system can be operated with fresh air, depending on the situation on-site, special requirements or targeted production figures. Yet another option is the recirculation of warm ventilation air in the area of the mid-air offtake to exclusively boost the mid-air temperature. However it is obvious that certain preconditions have to be met when recirculation comes into play. 5 Preconditions f or recirculation 5.1 Grate drive One important aspect is the absence of temperature or dust sensitive parts under the grate in 3000 Vd 6000 Vd 9000 Vd 12000 Vd Standard Recirculation Standard Recirculation Standard Recirculation Standard Recirculation reci rculation 2.0 7.6 2.27 11.2 2.0 15.3 2.27 22.5 2.0 22.9 2.41 34.5 2.0 30.6 2.28 45.1 13