Cement, Energy and Environment

• ' ' > ' Recirculation and Waste Heat Recovery Systems Thomas Weiss Reinhard Koehler IKN GmbH, Germany Summary Recirculation is a proven approach to boost the performance and to increase the output of a WHR solution within the cement plant. It also helps to eliminate an existing or to avoid an additional emission point. Further savings can be realized through the increased secondary/tertiary air temperatures. In case of recirculation , increased power consumption is more than compensated by the higher amount of energy in the mid-air duct. However, a higher recirculation air temperature has to be taken into account for this approach. A Pendulum Cooler® from IKN is highly suited to cope with that challenge, since its general construction allows for higher recirculation temperatures. A tailor-made design of the cooler offers manifold variants involving mid-air and vent-air tapping depending on the individual requirements or priorities of a plant. 1 Introduction Nowadays cement plant operators all over the world are striving for energy efficiency and environmental compliance. When it comes to energy efficiency, many waste heat recovery systems (WHRS) have been put in place in the last few years and are operating successfully. Most of them, especially in Asia, are based on the water steam process. There are a few plants operating with power circuits based on the Organic Rankine Cycle (ORC). A main reason for installing a WHRS is often generally the power supply itself, besides the payback based on the energy it is producing. But how large is the fraction of energy a plant can produce for its own? configuration is most promising when dealing with a WHRS. In doing so, we compare a standard configuration of cooler in a cement plant with another option, the recirculation of vent air back to the cooler. This concept offers certain benefits for the production of electricity while, in turn, imposing certain challenges for the plant layout and technology or design. The first new ventless Pendulum Cooler® from IKN was installed at Steetley Dolomite's Whitwell plant, UK, in the middle of 2013 (Fig. 1 ). • • • In this article, we investigate different design models of clinker coolers and capacities. To quantify different scenarios and the effect of different ventilation concepts, we systematically check which Fig. 1 /KN cooler at Whitwe/1/UK operating with recirculation I I