OCR Text |
Show Fig. 6 shows the configuration of baffles included in the flue of a 107 ft3 furnace at Hi-Tech Ceramics. The incinerator is used to combust the organic by products of binders and the polyurethane foam precursor used to make the reticulate. Fig. 7 shows the thermal profile along the length of the flue. Of particular note is thermocouple 3 which was located on the face of the baffle and indicated temperataures approaching 1800 deg F. It is believed that the baffles create improved mixing and better heat transfer to the gases, thereby promoting complete combustion. The surface of the LAS baffle after one year of operation shows signs of melting, suggesting combustion may be occurring at the surface resulting in temperatures in the 2400 deg F range. Future efforts will identify the actual gas analysis with and without the baffles. Currently there are two other installations incorporating this design, one on a ceramic kiln, the other at a drug company treating the acetone and alcohol by products of a drying operation. Figure 8 shows typical baffle components. An alternative to low NOx burners is the treatment of flue gases with ammonia in a catalized reaction which results in nitrogen and water. The catalyst support must be inert, withstand the thermal environment, have low pressure drop and provide sufficient surface area to meet space and cost requirements. Reticulated ceramics meet these requirements and are under evaluation in this application. The advantage offered by reticulated ceramics is the tortuous path which can provide increased communication between the gases and catalyst. Reticulated ceramics are also in use as an integral part of diesel particulate trap systems. Fig. 9 shows two such configurations. The cylindrical shape in the foreground is a prototype trap design. The primary advantage of reticulated traps is the lower temperature, more uniform regeneration process. The disk to the back and right is a flow through heat shield which is placed in front of the heating element and trap to prevent upstream heat damage during regeneration. SUMMARY The commonality of the applications discussed in this paper is the unique structure of the reticulated ceramic. The continuous pore phase allows for flow through characteristics for gases (or liquids) and the continuous solid ceramic provides rigidity and bulk properties. The phases are arranged in such a manner as to provide intimate and frequent contact between the solid and gases. This contact can be used to transfer heat energy, promote reactions or trap particles. |