Research Of Low NO_x Swirl Combustiin Technology Of 600MW Unit Boiler Burning With Bituminous Coal

With the rapid development of the economy,and the increase of electricity consumption,a large number of new power stations emerged at the historic moment,but its environmental problem was once neglected.Following the introduction of new environmental protection requirements in 2012,the stricter requirements of the environmental protection index of the power station boiler were put forward.On this background,this paper respectively studied the low NO_x swirl-flow combustion technology of domestic some 600 MW subcritical unit boiler and some 600 MW supercritical unit boiler,in order to solve the problem of higher NO_x p roduced due to combustion in the factory,and provided the reference for low NO_x combustion technology of the boiler of the same type.The low NO_x swirl combustion technology research was carried out mainly from two aspects of the boiler thermodynamic calculation and field industrial test.Field industrial test of boiler includes cold industrial test and hot industrial test.The influence of different over fire air blade angles,over fire air ratio and burner blade angle on boiler combustion and low NO_x formation was analyzed in the hot industrial test,and the following results were obtained on this basis:(1)On the 600 MW subcritical unit boiler,the influence of burner elevation moving down on the steam temperature was studied through thermodynamic calculation.Assuming that the flame height reduced 3.5 m,and the over fire air didn’t increase,thermodynamic calculation found that boiler desuperheating water discharge under various operating conditions reduced,but there was the input of a small amount of desuperheating water;Under BMCR working conditions,it is concluded that the overall fume temperature level didn’t reduce through thermodynamic calculation,so that there would be no lower steam temperature.(2)Cold industrial test showed that through th e recirculation zone state under different outer secondary air blade angles,we found that with the increase of blade angle,the center reflux area would be smaller;Through the test under different over fire air swirl vane angles,when the angle was 25 ° reflux area was obvious,helpful for burning;Powder tracer test proved primary wind speed was reasonable,which can carry the powder to the center of furnace;(3)Hot-state research was conducted respectively on the subcritical unit boiler and supercritical unit boiler.For 600 MW subcritical unit boiler,under 600 MW load conditions,NO_x formation reduced in different degree as the increase of over fire air vane angle,and the largest drop reached 44% under the working conditions of 45 °,while finally boiler efficiency was basically flat than before due to the decrease of exhaust gas temperature and the increase of fly ash carbon content;For 600 MW supercritical unit boiler,the influence of different outer secondary air blade angles on furnace slagging was studied,eventually when the blade angle was adjusted to 40 °-45 ° slagging was mild.Under different loads,the influence of different over air fire baffle bellows and burner blade angle on boiler combustion was studied;In comprehensive consideration of the boiler fly ash carbon content,NO_x emission situation,boiler slag carbon content and better operation parameters,we eventually determined the burning bellows baffle opening was at 30%,burner outer secondary air blade angle was set at 40 °.