| This article focuses on the tangentially fired boiler. Tangentially fired boiler plays a very important part in the power plant, which occupies more than 80% of the capability of all the boilers in power plant. Therefore, although its unit formation of NOx is less, it contributes more to all the NOx's drainage. Especially as the restrict of the environment protecting is being stricter, it's very urgent for us to control its NOx drainage.Among kinds of de-NOx technologies, flue gas de-NOx technology is regarded to have the better effect. To select an economic and effective technology earns especial emphasis by reason of its great investment. Basing on this, the article studies the de-NOx technologies from the macroscopical aspect. All the work of the paper fix attention on SCR, SNCR and SCR/SNCR. In addition, it also introduces a kind of techno-economic method which is of great signification for the decision-making of power plants to invest in de-NOx equipments. Mostly, for the technological analysis, the designed parameters of the three and their impacts on the operation of existing equipment in power plants are taken into consideration; For the economical analysis, aiming at two power plant, compare through calculating the annual fee, unit charge for de-NOx, as well as the effect of charges for disposing pollutants and loan policy on de-NOx expense. The application of dynamic model of economics in the economical evaluation of de-NOx equipment, can surely provide important reference for the preliminary dicision-making and feasibility study of power plants.Lucubrating the mechanism of NOx formation contributes more to the debasement of NOx drainage. In past, the work mainly bases on the experience of the boiler in power plant and the measured data about some small boilers built for experiment, but all these have great localization because of the complexity of the airflow of pulverized coal and the restriction of the measure technology. Furthermore, the study through experiment needs more manpower, material and financial recourses, as well as longer period. Along with the development of computer, numerical simulation becomes a very important means to study the combustion and contamination's formation, due to its time saving, lower cost and integrated data.Adopting the MB-FRR boiler produced by Mitsubishi as the study object, the paper simulated the distribution of NOx under six different conditions relatively after considering the NOx formation mechanism and appropriate mathematical models. |
