Obiettivo The project is aimed at the new application of an advantageous energy efficient clean technology to the pulverized combustion of lignites/brown coals. The technology is based on an axial swirl staged combustion technique developed for the firing of bituminous coals. It has already been proven, on a 660 MW(e) utility boiler, to significantly reduce NOx emissions without any significant reduction in plant efficiency whilst firing bituminous coals. The improved control of fuel air mixing achieved with the Low NOx Axial Swirl Burners results in a reduction in slagging and fouling problems, thus leading to increased plant availability.The low NOx burner was tested over a wide range of firing conditions on a low ash lignite and a high ash lignite, with variation of fuel transport stream oxygen and moisture conditions over the range likely to be encountered in typical utility and industrial applications.It was not possible to identify an acceptable firing regime for the high ash fuel but it was possible to identify acceptable performance conditions for the low ash fuel.The standard low NOx burner produced NOx emission levels of 230-250 ppm at 3% O2 dry) when operating with low levels of moisture in the transport gas and furnace exit excess air levels of approximately 25%, this level of excess air being required to produce acceptable levels of CO and carbon in ash.At higher levels of transport gas moisture it was necessary to modify the standard low NOx burner to enhance flame stability, the modification resulting in a NOx emission level of approximately 400 ppm.This work has shown that it would be possible toapply the Babcock Energy Low NOx Axial Swirl Burner to certain lignite firing applications with relatively minor modifications to the existing standard burner. However, for applications involving very high ash fuels or very low oxygen/high moisture transport medium use of the standard low NOx burner under direct firing operation without separation of some of the fuel stream moisture would not be appropriate. Under these circumstances more extensive modifications to the burner would be required. The extent of such modifications has not been investigated in this project.Earlier types of low NOx burners relied mainly on delaying the rate of mixing of combustion air and fuel thus reducing the availability of oxygen for combination with fuel nitrogen in the early stages of combustion. This approach often led to slower rates of combustion and reduced levels of burnout, hence reducing the overall plant efficiency.Babcok Energy Limited have developed a Low NOx Axial Swirl Burner which has been demonstrated to significantly reduce NOx emission levels and contrary to trends in many places the installation of these burners demonstrated that significant NOx reductions can be obtained without any significant reduction in plant efficiency and availability.This development is now being commercially exploited both in the UK and worldwide for the clean efficient combustion of bituminous coals. It is believed that the basic burner design is also suitable for the clean efficient combustion of brown coals or lignites. Due to the differences in properties of lignatious and bituminous coals there is however a significant residual risk involved in the application of the Babcock Energy Limited Low NOx Axial Swirl Burner technology to the pulverized combustion of lignatious coal. This project was therefore aimed at the new application of this advantageous energy efficient clean technology to the pulverized combustion of lignites.It was recognised that with the risks and the high costs involved in retrofitting a large utility plant with lignite firing Babcock Energy Low NOx Axial Swirl Burners, it would be very difficult to persuade any potential host plant to take part. The Babcock Energy Large Furnace Facility in Renfrew, Scotland was used to test the performance of a full size 35-40 MW (t) Low NOx Axial Swirl Burner on lignite firing.The facility was modified to replace the existing primary air system with a recycled flue gas system. Testing involved the design, supply, installation and testing of a Low NOx Axial Swirl Burner firing lignite. Programma(i) ENG-THERMIE 1 - Programme (EEC) for the promotion of energy technology in Europe (THERMIE), 1990-1994 Argomento(i) 7.6 - ULTRA-CLEAN COALS AND WASTE MANAGEMENT (WM) Invito a presentare proposte Data not available Meccanismo di finanziamento DEM - Demonstration contracts Coordinatore Mitsui Babcock Energy Ltd (MBEL) Contributo UE Nessun dato Indirizzo Technology Centre High Street PA4 8UW Renfrew Regno Unito Mostra sulla mappa Costo totale Nessun dato
