Analyzing the Effect the Fuel Oil Characteristics and Combustion Conditions Have on the Yield of Vanadium Pentoxide

Abstract

An approach to elaborating a computation method for determining the content of vanadium pentoxide in the combustion products from gas- and-oil-fired boilers is considered within the framework of clarifying the contribution this substance introduces in the overall toxicity of flue gases. The need of such assessment is stemming from the fact that vanadium pentoxide is a substance related to the first class of hazard along with carcinogenic polycyclic aromatic hydrocarbons. To justify the extent to which the vanadium pentoxide emission must be reduced, it is necessary to determine the contribution of individual fuel components and the fuel oil combustion conditions in the environment pollution intensity. Calculation dependences that make it possible to consider the important energy and performance characteristics of thermal power boilers and the fuel used in them are proposed. Fuel oils of various grades and relating to different classes of sulfur content are selected as fuels under study to analyze the effect the component composition of fuel oil has on the amount of vanadium compounds generated in the combustion products. It has been found that the content of vanadium pentoxide in the boiler smoke gases depends directly on the vanadium concentration in the source fuel. No additional amount of vanadium is generated in the combustion products in the course of alternative chemical reactions and transformations. It has also been found that a significant effect of reducing vanadium emissions into the environment during the operation of fuel combusting installations is achieved through the use of expensive catalytic gas purification systems. It is pointed out that, in order to achieve more efficient reduction of vanadium pentoxide emissions into the atmosphere, is necessary to decrease the emission of sulfur-containing components of flue gases. Data on the content of sulfur in the source fuel allows, to a considerable extent, a conclusion to be drawn on the possibility of vanadium pentoxide to be produced at the fuel combustion stage and in the flue gases. The levels of vanadium pentoxide emissions have been determined for certain designs of gas-and-oil-fired boilers taking into account the effect of incomplete combustion, the fraction of unburned carbon, and fuel burnout degree in the combustion device. In the nearest future, improvements in the environmental safety of thermal power plants in Russia will be connected with introduction of best available technologies that will make it possible to standardize the emissions of harmful substances into the atmosphere from the standpoint of sanitary-hygienic requirements, process parameters and characteristics of domestically produced boiler units.