80 MW煤粉工业热水锅炉快速启停特性

Investigation on on-off characteristic of 80 MW pulverized coal industrial water boiler

  • 摘要: 燃烧器通常被认为是煤粉锅炉的核心设备,并逐渐成为灵活调峰中锅炉启停过程研究的重点。一种逆喷旋流燃烧器以其良好的稳定燃烧特性,广泛应用于中小型煤粉锅炉,以满足宽负荷、频繁启停运行的要求。以采用双锥预燃室逆喷旋流燃烧器的80 MW煤粉锅炉为对象,以采暖运行中运行负荷、供料频率、炉膛平均温度及选择性催化还原(SCR)系统烟气温度的实际测量数据为依据,对不同初始条件的启炉过程和正常停炉过程进行详细分析。结果表明,该煤粉炉具备较为快速的启停能力,其中启炉过程根据供料频率的变化分为负荷快速提升、负荷缓慢提升阶段,快速提升阶段,负荷提升率可达到3%/min以上,在冷态和热态启动(即回水温度低和高)的情况下,锅炉负荷提升率分别达到3.6%/min和3.11%/min。启炉阶段的负荷提升速率受限于煤粉燃烧速率与炉膛传热速率的不匹配性,即传热速率滞后于燃烧速率,而煤粉燃烧速率则受储仓式煤粉供料系统供料频率的限制。热态情况提升至满负荷时,传热的滞后性体现为13.18 MW的负荷升高,占额定负荷的16.48%。同时热态情况下的炉膛上、中、下部烟气平均温度高于冷态情况,但温度上升速率低于冷态情况;并且可以在较低负荷及较短时间内达到SCR反应所需的温度区间。停炉阶段,受益于供料频率的快速切断,负荷降低可分为快速和缓慢阶段,降低速率分别为9.69%/min和1.09%/min,炉膛平均温度与SCR烟气温度快速下降,实现快速停炉。

     

    Abstract: The burner is usually considered to be the core equipment of pulverized coal boiler, and gradually become a priority in the research of on-off process of boiler. A kind of reversed-jet swirl burner is widely used in the medium-mini pulverized coal boiler to satisfy a wide operating load and a frequent on-off process due to its better stable combustion characteristic. In this paper, the 80 MW pulverized coal boiler, which adopts the reversed-jet swirl burner with double cone pre-combustion chamber, was investigated. On the basic of the measured data of operating load, feed frequency, the flue gas average temperature in furnace and the selective catalytic reduction (SCR) system, the star-up with different initial conditions and normal shut-down process was analyzed. The results show that the pulverized coal burner had a rapid on-off ability. The start-up process was divided into stages of load rapidly increase and slowly increase based on the changes in feed frequency. In the load rapid increase stage, the rising rate of operating load could reach over 3.0%/min. The 3.6%/min and 3.11%/min could be achieved on the rising rate of operating load for the cooling and heating star-up (CS and HS) case of furnace respectively, where cooling and heating mean the low and high temperature of return water condition. During the star-up process, the rising rate of operating load was limited by the mismatch of burning rate of pulverized coal and heating transfer rate of furnace. It indicated that the heating transfer rate lagged behind the burning rate. And the burning rate of pulverized coal was limited by the frequency of storage-type pulverized coal feed system. In the HS case, when the operating loads reached at a rated design value, the lag behind of heating transfer rate was reflected in 13.31 MW operating load increasing. The flue gas temperature in the upper, middle and lower parts of furnace for the HS case is higher than that for the CS case, but the rising rate of flue gas temperature is lower than that for the CS case. And it can enter the temperature region early to make SCR reaction. During the shutdown process, with the help of rapid cut-off of the feed system, the reducing rate of operating load was divided into rapid and slow stages with reducing rates of 9.69%/min and 1.09%/min respectively. The flue gas temperature in the furnace and SCR system decreased rapidly, the shutdown process was rapidly reached.

     

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