環保煤儲存自燃問題之研究

Abstract

煤炭具有蘊藏量高、發電成本低、投資報酬率高、爭議較核電廠少等優勢，但燃燒後有排放污染的環保問題，需藉由環保設備來改善，以符法令規範。而環保煤(enviro-coal或稱低灰特低硫亞煙煤) 可使一般鍋爐勿需藉由外加之環保設備，就能維持現今煙囪排放物符合環保標準，在社會大眾對環境品質的要求日益提高以及政府分階段公告日趨嚴格之煙囪排放標準下，環保煤將是絕佳的燃料選擇。 惟環保煤揮發物含量高、粒徑小、易氧化蓄熱，於儲存、輸送過程極易發生自燃及煤塵飛揚之現象。本論文是以印尼生產之adaro環保煤，儲存在台中發電廠開放式的煤場中，以簡單的現場實驗及觀察分析，得到煤堆內部溫度分佈的情形及煤堆蓄熱溫升的趨勢，並推論表面水份含量及周圍風速，將是影響煤堆溫升速率的主要原因。希望藉由本論文能提供煤場管理人員參考應用的資訊，以避免發生自燃致生不必要的損失，並減少意外及環境污染，使此類煤能廣泛而安全的使用。

While enjoying the advantages of having high reserves, low electricity production cost, high investment return, and much less nuclear-reactor-type of disputes, the use of coal fire nevertheless is tarnished by the fact that its burning release would cause serious contamination of the environment. The latter normally is required to be sized down via great size-up of all related post-processing facilities in order to comply with the environmental regulations. A new type of coal, enviro-coal (or, low-ash, low-sulfide-aerosol coal) has emerged and proved that, by using it instead, the as-released chimney outputs from normal boilers can already meet the environmental guidelines without having to incorporate further post-processing units. Therefore, in the global trend of increased public demand for a cleaner earth and subsequent much tighter environmental laws, adoption of the enviro-coal is seen to be a much better, likely inevitable alternative. However, the highly volatile, small-size particulate characteristics of the enviro-coal still is susceptible to oxidation and thus latent heat generation, which constitute great concern over the somewhat high risk of spontaneous ignition (or combustion) during its storage and transport. This thesis aims to study the internal temperature distribution and the tendency of spontaneous heat generation of a pile of enviro-coal (adaro, produced in Indonesia) situated in the open field of Tai-Power Taichung Thermal Power Plant. It is found that, via on-site measurements and coal content analyses, the surface water content of the enviro-coal and its surrounding wind speed are the two main factors deciding the rate of the internal heat generation and thus the subsequent temperature rising. It is hoped that the information disclosed by this current study may serve as an important safety reference to the coal field administration staff in general and in the end promote the wide-ranged use of the promising new alternative: enviro-coal.