Combustion of municipal solid waste in fluidized bed or on grate - A comparison.

Grate firing is the most common technology used for combustion of municipal solid waste. The more recently developed fluidized bed (FB) combustion is rarely employed for this purpose. The present work compares the technical properties of the two devices to find out why FB has not been more used, considering the recent importance of waste-to-energy. Several drawbacks of FB, the need for fuel preparation and bed material consumption, play a role, but these features also have advantages: combustion is improved by the sorted fuel and less ashes. Silica sand as a bed material has the positive property of being an alkali scavenger. If replaced by an oxygen carrier (e.g. ilmenite) the scavenging effect increases, and, in addition, oxygen carriers even out the non-combusted gaseous fields in the furnace, which improves combustion and allows higher steam data at a given corrosion level. There are other advantages of FB, such as end-superheaters in the circulation loop, heated by the bed material. However, also the environmental performance and energy efficiency of grate firing has been improved, and several advanced solutions have been proposed. In conclusion, it is not clear which of the devices that is the better one. An economic evaluation is made, based on available literature information, but still there is no clear winner.

A Protocol for Helicopter In-Cabin Intubation.

OBJECTIVE: The gold standard for prehospital intubation is to avoid intubating in confined spaces. For our helicopter service, this is not always realistic. Operating in a rural region with a subarctic, cold climate, our crews are frequently forced to intubate inside ambulances or in our helicopter. This article describes a protocol for in-cabin intubation and compares it with standard open space conditions. METHODS: Fourteen prehospital physicians were randomized to solve a simplified clinical scenario during which they were to intubate a mannequin either inside the helicopter, in accordance with our in-cabin protocol, or outside on an ambulance stretcher. Participants scored intubating conditions using a visual analog scale (VAS) and the Cormack-Lehane classification. The number of intubation attempts was recorded. Three timing end points were also measured. RESULTS: All intubations were successful on the first attempt. All participants reported an optimal glottic view of Cormack-Lehane 1 in both scenario conditions. Participants perceived in-cabin intubation to be less difficult than intubating outdoors. (VAS 1 vs. VAS 2, P = .02). We found no difference in the duration of intubation. Scene time was 53.5 seconds (P = .04) shorter in the in-cabin group. In-cabin intubation delayed the establishment of a secure airway by 63 seconds (P = .01). CONCLUSION: Our study suggests that protocolized in-cabin intubation can be performed in a timely manner under conditions that are equal to or better than when intubating outside on a stretcher with 360-degree patient access. Although delaying the establishment of a secure airway, in-cabin intubation may reduce scene times.