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A New Achievement Made in Down-Fired Boiler Combustion Technology
Publisher:刘彬  Publishing Time:2016-02-29   Views:13

The latest research article of the research team directed by Professor Li Zhengqi of our school, Industrial Application of an Improved Multiple Injection and Multiple Staging Combustion Technology in a 600 MW Supercritical Down-Fired Boiler was published in Environmental Science & Technology (Impact Factor: 5.330), an internationally recognized journal in the environmental field. HIT stands as both the first signature affiliation and the corresponding author affiliation.

Despite the fact that the down-fired boiler designed for lean coal and anthracite in China occupies more than 80% of the total market share in the world, there still exist various problems in its operations, such as seriously skewed flame kernel in lower furnace, large wall temperature differences in the water wall,fairly high NOx emission concentration (reaching up to 1200-1600 mg/m3 at 6% O2) and poor coal powder burning (carbon in fly ash reaching to 8-15%). Such problems have negative effects on the operation of the down-fired boilers in terms of safety, environmental friendliness and economical efficiency.

The multiple injection and multiple staging combustion (MIMSC) technology proposed by Li’s research team aims to solve the above-mentioned problems in down-fired boilers. When applied on a 600 MW supercritical down-fired boiler, the industrial measurements reveal that under the condition of burning anthracite (dry ash-free basis volatile being 10%), the following effects were recorded: over-fire air (OFA) damper opening changed from 20% to 70%; The flame kernel in the lower furnace was symmetric; Boiler thermal load was evenly distributed; The wall temperature difference in the water wall was brought down; The ignition distance of the fuel-rich coal air flow was reduced from 1.05 to 0.66 m; The content of combustible in fly-ash increased from 5.65% to 6.4%; NOx emissions of furnace outlet decreased from 702 to 575 mg/m3 at 6% O2; Exhaust gas temperature at the air pre-heater outlet rose from 126.5 to 129 °C; Boiler efficiency was down from 90.1 to 89.7%; Carbon in fly ash and NOx emissions in optimum operating conditions attained levels of 6.18% and 589 mg/m3 at 6% O2. It was evident that the safety, environmental friendliness and economical efficiency of the boiler’s operation have greatly improved. The research result is of great significance to researching and developing our own down-fired boiler combustion technology with exclusive independent intellectual property rights.

This research was supported and funded by the Foundation of National 863 Plan of China, National Natural Science Foundation of China, and Foundation for Innovative Research Groups of the National Natural Science Foundation of China, and Harbin Boiler Company Limited.