The Cold Simulated Experimental Study On NOx Reduction In Pulverized Coal Boiler Using Natural Gas Reburning Technology

Mixing characteristic of airflows in a tangential pulverized coal-fired boiler where the natural gas reburning technology was used to control NOx production was discussed in this thesis. The experimental study was carried on the cold module that was designed and built by us. The temperature distribution in the furnace of cold module was used to simulate the concentration field of mixed airflows. The mixture characteristic (temperature distribution) of reburning air (hot air) and main airflow (cold air) was measured and gotten with a computer data acquisition system -and data processing software.In this paper, emphasis was put on the mixed characteristic under the conditions of various parameters, such as, various reburning nozzle arrangement program(front & back wall arrangement and tangential arrangement), various arrangement height, various air flow rate and various mixed time. Finally, the experimental results were analyzed and summarized, as well as industrial applying prospect.This paper mostly deduced the following conclusions:(1) When the natural gas reburning technology were adopted on a tangential pulverized coal-fired boiler, There was a better value for recirculating flue gas rate needed in natural gas transportation. The value should be between five percents and seven percents.(2) According to the result of cold state experiment, considering of the stability of dynamical field in the practical boiler, the setting mode of reburning gas nozzle had better adopt tangential arrangement to a tangential pulverized coal-fired boiler.(3) When the natural gas reburning technology were used in a boiler reconstruction, it was considerable to spout reburning gas through third air nozzles. However, the shape, section and angle of original third air nozzles needed to be changed.(4) According to the investigation of mixed effect of reburning zone, overfire air nozzle arrangement should be in the relatively higherposition. For a 100MW prototype boiler referred to in this paper, the position should be at least 2.5m higher than the position of reburning gas nozzle.