Numerical Simulation Of Oxy-Fuel Combustion On 300MW Tangentially Fired Pulverized-Coal Boiler

China, whose power industry is dominated by coal-fired power generation, is a big country of coal production and coal consumption. One hand, coal industry has a great help to promote economy growth of China continuously and quickly, but on the other hand, it brings environmental problems, such as the CO2 emission of China has became the first in the world. On the background of global warming, China must reduce greenhouse gas emissions and adopt a new energy-saving and emission reduction technology.Oxygen rich combustion technology, as a kind of efficient clean combustion technology which can effectively control the emissions of greenhouse gases and pollutants, has gradually attracted people’s attention. At present, oxygen rich combustion technology has been recognized by many countries, and has made some progress in theory and engineering applications, but it’s still in the primary stage, and there are many technical problems to be resolved. To study the technology of oxygen enriched combustion, the traditional experimental method needs to set up a large scale test bench, which will have a long cycle and high cost, but computer numerical simulation can solve the problem effectively. With increasing speed of computer and maturity of numerical simulation software, the numerical simulation results are more accurate, and it has important guiding significance to the engineering practice.In order to have a better understanding of the combustion characteristics in the furnace under O2/CO2 atmosphere, a 300 MW tangentially fired pulverized coal boiler is taken as the research object, the three-dimensional structure of the furnace was established and the grid was generated by the ICEM software, the appropriate mathematical model was selected in the software of fluent, respectively in air and O2/CO2 atmosphere, flow in the furnace, heat transfer, combustion and emission characteristics were numerically simulated. results showed that with the O2 concentration of 21%, O2/CO2 atmosphere in the furnace temperature level was far lower than the air, the flame center moved upwards, the combustion characteristics became poor; Under O2/CO2 atmosphere, with the O2 concentration increased, the furnace temperature and the combustion characteristics were obviously improved, O2 concentration of 29% had the best combustion status; NOx produced by temperature and O2 concentration, with O2 concentration 21%, NOx concentration under O2/CO2 atmosphere was lower than that under air atmosphere, it increased with the rise of O2 concentration; The total amount of flue gas in the furnace was reduced, and the smoke exhaust loss was reduced; CO2 concentration of dry flue gas could reach above 90%, which would be captured easily. The effect of the enthalpy of flue gas on the flue gas temperature of the furn, effect of low load operation on combustion stability, and the influence of air leakage on the simulation results were studied under different conditions.The economy of the oxygen enriched combustion were evaluated. One hand, the oxygen cost was quantitatively compared with the nitrate removal cost, which pointed out that the cost of oxygen is lower on the condition of achieving the same effect of nitrogen. On the other hand, it pointed out that the oxygen enriched combustion capture CO2 more efficiently and cost less than traditional NH3 absorption method, so the oxygen enriched combustion had the advantages of economic and environmental protection.