RESUMEN
Traditionally EfW (Energy from Waste) plants apply a reciprocating grate to combust waste fuel. An integrated steam generator recovers the heat of combustion and converts it to steam for use in a steam turbine/generator set. This is followed by an array of flue gas cleaning technologies to meet regulatory limitations. Modern combustion applies a two-step method using primary air to fuel the combustion process on the grate. This generates a complex mixture of pyrolysis gases, combustion gases and unused combustion air. The post-combustion step in the first pass of the boiler above the grate is intended to "clean up" this mixture by oxidizing unburned gases with secondary air. This paper describes modifications to the combustion process to minimize exhaust gas volumes and the generation of noxious gases and thus improving the overall thermal efficiency of the EfW plant. The resulting process can be coupled with an innovative SNCR (Selective Non-Catalytic Reduction) technology to form a clean and efficient solid waste combustion system. Measurements immediately above the grate show that gas compositions along the grate vary from 10% CO, 5% H(2) and 0% O(2) to essentially unused "pure" air, in good agreement with results from a mathematical model. Introducing these diverse gas compositions to the post combustion process will overwhelm its ability to process all these gas fractions in an optimal manner. Inserting an intermediate step aimed at homogenizing the mixture above the grate has shown to significantly improve the quality of combustion, allowing for optimized process parameters. These measures also resulted in reduced formation of NO(x) (nitrogenous oxides) due to a lower oxygen level at which the combustion process was run (2.6 vol% O(2,)(wet) instead of 6.0 vol% O(2,)(wet)). This reduction establishes optimal conditions for the DyNOR™ (Dynamic NO(x) Reduction) NO(x) reduction process. This innovative SNCR technology is adapted to situations typically encountered in solid fuel combustion. DyNOR™ measures temperature in small furnace segments and delivers the reducing reagent to the exact location where it is most effective. The DyNOR™ distributor reacts precisely and dynamically to rapid changes in combustion conditions, resulting in very low NO(x) emissions from the stack.
Asunto(s)
Contaminantes Atmosféricos/análisis , Contaminación del Aire/prevención & control , Gases/análisis , Incineración/métodos , Eliminación de Residuos/métodos , Administración de Residuos/métodos , Fuentes Generadoras de Energía , Monitoreo del Ambiente , Alemania , Calor , Modelos Teóricos , Oxidación-Reducción , Residuos Sólidos/análisis , SuizaRESUMEN
INTRODUCTION: Complex vertebral fractures can lead to injury of the spinal cord with resulting paraplegia. High-speed accidents are common causes, especially in younger patients. Malignant or inflammatory processes play an important role in the elderly. Less common reasons for a spinal cord injury are congenital malformations. We here report about a 17-year-old patient who suffered from paraplegia after an isolated rupture of the spinal cord without an injury of the vertebral bodies, intervertebral disc or ligamentous structures. This type of injury has not been reported in the literature before. PATIENT AND METHOD: We report about a 17-year-old patient, referred to our hospital, presenting with lumbal paraplegia after a high-speed accident 8 days prior to admission. After initial stabilisation of the polytraumatised patient, he was referred to our hospital for further treatment. RESULTS AND CONCLUSION: The radiological examination showed a bilateral acetabular fracture, a right anterior pelvic ring fracture and shaft fractures of the left humerus and right femur. Furthermore, the spinal cord at thoracic level 10/11 was ruptured. Interestingly, there was no injury of the vertebral bodies, intervertebral disc or ligamentous structures. A tethered cord as a possible anatomic variation could be excluded in this case by MRI. However, anatomic variations could be the reason for this injury and should be kept in mind.