渦旋式流體化床燃燒爐中床內燃燒份額之研究

Study of In-bed Combustion fraction in a Vortexing Fluidized Bed Combustor

楊智雲(Chih-Yun Yang)

指導教授 ： 錢建嵩

中原大學/工學院/化學工程研究所/碩士(2015年)

https://doi.org/10.6840/cycu201500923

摘要

對流體化床鍋爐而言，熱傳管的安排佈置是設計爐體的一大重點其會受燃料於爐內不同區段之釋熱量有很大的影響。同時將燃料於不同區段之釋熱量稱為燃燒份額，可由各區段之耗氧量求之。
本研究使用兩種不同之燃料：煤及刺竹，探討燃料特性與操作變數對床內燃燒份額之影響。於0.8 m長×0.4 m寬×4.7 m高之先導型渦旋式流體化床中進行實驗，將煤及刺竹分別於固定釋熱量130,000 kcal/hr，一次風總風量3 Nm3/min，二次風總風量2 Nm3/min，並在煙氣迴流模式下，改變床下計量氧及粒徑大小，探討操作條件對床內燃燒份額、污染物排放等影響，同時經本實驗室多年來研究燃燒份額之成果，迴歸各實驗數據得一經驗式，可用來模擬及預測各操作變數下，床內之燃燒份額。
實驗結果顯示，對於所有燃料而言，床內之燃燒份額隨床下計量氧增加而增加；煤隨粒徑增大，其床內燃燒份額亦隨之增加；在相同操作條件下，生質物之床內燃燒份額低於煤，係由於生質物含有高含量之揮發份，投料後揮發份易於較高之區域燃燒。此外，經數據迴歸後得床內燃燒份額之經驗式 ，在實驗值與迴歸值之比較上，其平均偏差為13.8%，標準偏差為18.7%，其結果能有效預測及模擬，不同燃料於不同操作參數下之床內燃燒份額，而各操作參數敏感性大小為: 二次風配風比 > 床下計量氧率 ≈ 床溫 > 燃料特性 ≈ 燃料粒徑。

關鍵字

流體化床燃燒爐 ； 床內燃燒份額

並列摘要

An arrangement of heat exchanger is a key point in the design of fluidized boiler. This arrangement is depend on the amount of heat released in each section of the combustor, including bubbling zone and freeboard zones. In addition, heat release rate is defined as the amount of heat released in each section of the combustor. Heat release rate can be calculated from the oxygen consumption of each section per total oxygen consumption. The purpose of this study is to investigate the relationship between in-bed heat release rate and fuel properties, such as particle size, volatile/fixed carbon ratio. The effects of in-bed stoichiometric oxygen ratio on in-bed heat release rate are also investigated.
Combustor can be divided into two regions from bottom to top, namely, bed zone and freeboard zone. The two types of fuels, coal and thorny bamboo are used as feeding material. The particle size of the coal ranges from 854 to 3644 μm. The operated in-bed stoichiometric oxygen ratios are between 80% and 100%. Total primary air is 3 Nm3/min and the secondary air is 2 Nm3/min. The excess oxygen ratio was kept at 40%. The silica sand is used as the bed material.
The experimental result shows that the in-bed heat release rate is increased with the decreasing volatile/fixed carbon ratio in all fuels. As the mean particle size is increased, the in-bed heat release rate is also increased. Here we regress the data to build the empirical equation, . It can be summarized that the effect of fuel properties on the in-bed heat release rate is insignificant.

並列關鍵字

Fluidized bed combustor ； In-bed heat release rate

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