玉米穗軸焚化爐三維流場模擬

Simulation of the Three-Dimensional Flow Field in a Corncob Incinerator

吳中興(Chung-Hsing Wu)

《農業機械學刊》 3卷3期 (1994/09) Pp. 1-14

https://doi.org/10.30062/JAM.199409.0001

摘要

在飼料玉米之生產過程當中，有大量體積之玉米穗軸廢棄物產生，若是不妥善處理，將污染環境。在各種處理方式當中，使用焚化爐，可以縮減體積，也能夠回收可觀的熱能，提供乾燥作業所需要之能源，並因此大幅減少由露天燃燒所造成之嚴重空氣污染現象。
本研究採用K-ε紊流模式，來模擬焚化爐內部燃燒室之三維流場。研究結果顯示，在相當廣闊之區域內，切向速度高於徑向速度，而且在部份圓截面上，有迴流區存在，因此以三維方式來探討燃燒室流場，可提高其準確性。
當二次送風口之噴射角度為135度時，大部份的區域，無顯著地迴流區產生，切向速度也不高，將使揮發性氣體混合不良，且滯流時間短，使燃燒不易完全。當噴射角度為等於或小於90度時，將在二次送風口下方，產生一廣大地迴流區域，而且當噴射角度愈小時，二次送風口上方之流速愈小，將延長氣體在燃燒室內之滯留時間，使廢棄物之燃燒結果，臻於完全。

關鍵字

玉米穗軸 ； 焚化爐 ； 三維模擬 ； 燃燒室

並列摘要

A large percentage of the corncob waste is obtained in the production of feed corns. If they are not well treated, our living environment will be polluted. The adoption of the incinerator is one of the choices to treat the waste. The volume can thus be substantially reduced, and the thermal energy could be recovered to supply the drying operation in the same time. The existing serious problem on air pollution from buring in the open field could also be avoided.
In this paper we adopt the K-ε turbulence model to simulate the 3-D flow field of the combustion chamber in a furnace. The results show that the tangential velocity of the fluid has a non-negligible effect on the flow field of the combustion chamber. The flow fields in the circular cross sections vary apparently with the heights and the injection angles. The recirculating phenomenon can not be observed in most regions of the combustion chamber in the case of the injection angle being 135°. It is not a good situation for the combustion. When the injection angle of the secondary air port is not larger than 90°, a wider recirculation zone appears below this height of the secondary inlet port. The flow velocity above this height will decrease as the injection angle to be smaller. This will lengthen the resident time of the mixture in the combustion chamber to promote the incineration of the organic volatile gases inside the simulated corncob incinerator.

並列關鍵字

Incinerator ； 3-D Flow field ； Numerical simulation ； Combustion chamber