Research On Combined Combustion Of Pulverized Coal And BFG In Power Boiler With Applications

Blast furnace gas (BFG) is a by-product in the process of ironmaking in iron and steel works. The content of carbon monoxide which is the main combustible component is low, meanwhile, it contains a great deal of nitrogen. So the calorific capacity of blast furnace gas is low, and its combustion is unstabilized. Now with the reinforcement of energy saving and environmental consideration, steel enterprise makes much account of reutilization of blast furnace gas. Using blast furnace gas for generating electricity has remarkable economic and social benefit.Combined combustion of blast furnace gas and pulverized coal is an effective way. But the difference of fuel and combustion characteristics between blast furnace gas and pulverized coal is vary large, which makes the co-fired boiler and pulverized coal fired boiler much different in burning organization, the dimension of fume and the arrangement of heating surface. In order to make the combined combustion of blast furnace gas and pulverized coal safe, stable and highly efficient, technical renovation for original boiler must be taken.The combustion characteristics of gas fuel, and the principle and measure of stabilized combustion are introduced in this text.The technical difficultises and countermeasures of combined combustion are contained also. The technology of stepped fire is emphasized specially.Use the basic clue and techonlgy above, technical renovation of combined combustion have been taken in WISCO. The operational logs manifest that: (1) in company with the increment of BFG co-fired, the temperature of export fume rises from 992℃up to 1008℃; (2) the temperature of superheated steam varise in a small range, lower than 540℃,which satisfies the requirement of stable operation. (3) when the BFG flow increases from 2.3m3/h up to 10.4m3/h, the funnel temperatures of both sides have a advancement of only 20℃and 18℃, which are lower than 167.4℃and meet the renovation requirement. It can be seen from the operational result that the renovation makes great effect of operation and energy saving. and it proclaims that the technology of stepped fire in backflow region is able to solve the technical matters of combined-combusion boiler.