Diagnosis Of Uneven Combustion Problem And Study On Combustion, Control And Optimization Of 1000MW Boiler

At present, the uneven combustion of furnace is the most difficult problems in thermal power generating units, especially in large capacity tower type boilers which have large scale cross section and low primary air speed, so the tangential circles are hard to intersect with another and leading to the uneven combustion. Uneven combustion will bring about coking, over-temperature of local metal, and unbalance of steam temperature which will have strong impact on the safety and economy of the units.As to these problems such as uneven combustion, over-temperature of local metal, and unbalance of steam temperature, based on the operation condition of a 1000MW tower type boiler, this paper analyses the reason that the large temperature difference of water cooled wall outlet, especially in the low load stage. The temperature difference of separator outlet is caused mainly by uneven combustion, so we need to ascertain the extent of uneven combustion, analysis the reason of uneven combustion, and seek for the strategy for combustion regulation.Using FLUENT, we made a numerical simulation to all the boiler data, calculated the temperature field, fluid field and components of every layer detailed. At the same time, actual temperature field is introduced according to measurement data, and the actual temperature field is in conformity with the simulated temperature field, so the truth and extent of uneven combustion can be confirmed. Based on the mass data modeling scheme, the relation model between temperature difference of separator outlet and each operation parameter is established, and the key parameters are also produced. Combined with the optimization model, the load-flow relation in the condition of secondary air damper open value of every corn in each layer in different load is developed. According to the full-load regulation test, a fine air distribution program proves to be effective. Optimizing control loop of burner’s secondary air, the temperature difference of water cooled wall outlet is in the acceptable range, and the problems of uneven combustion and temperature difference are reduced.