| 摘要: | 近年來一般家戶垃圾的收集量顯著的減少，使得在台灣的大型都市垃圾焚化爐，具有餘裕處理一般事業廢棄物，但由於進入焚化爐的垃圾性質和組成，產生極大的變化，使得酸性氣體污染物的排放濃度，經常發生起伏變化的情形。本研究為了瞭解酸性氣體控制設施之操作的穩定度，以台灣北部地區某大型都市垃圾焚化爐，採用半乾式洗煙塔去除廢氣中酸性氣體，做為實廠研究對象，藉以探討各項操作變數，包括化學藥劑種類、反應溫度及化學藥劑計量比，對於酸性氣體去除效率的影響，並以情境模擬實驗，了解維持廢氣處理系統穩定度的策略。
研究結果顯示，當廢氣反應溫度在150℃時，採用消石灰或氫氧化鈉作為化學藥劑，化學藥劑計量比分別在2.4及1.6時，對於酸性氣體中的HCl，均可達到96%以上的去除效率，SOx的去除效率，分別可達到86%及78%以上，不過隨廢氣反應溫度升高，酸性氣體中HCl及SOx的去除效率會逐漸下降。本研究亦發現，當廢氣反應溫度升高至210℃時，只有碳酸氫鈉，在化學藥劑計量比1.6時，對於HCl及SOx的去除效率，可以分別維持在96%及85%以上。
此另本研究結果指出，維持除酸系統功能穩定的策略，可藉由額外增設冷卻水噴入系統，依須要隨時控制廢氣反應溫度約在140~150℃之間，如此可以在最低的消石灰化學藥劑計量比下，得到最佳的除酸效率；增設一套乾式消石灰噴入系統，當廢氣中酸性氣體監測濃度發生較大變化時，可以立即調整增加化學藥劑計量比，以提高酸性氣體的去除效率。此外在垃圾儲坑，利用抓斗充份攪拌混和各類廢棄物，使投入焚化爐的進料性質，隨時維持在均勻穩定狀態。
;In recent year, the collected amounts of the general household solid wastes decreased significantly, thus the large municipal solid waste incinerators (MSWI) in Taiwan have headroom capacity to handle the general industrial solid waste. Consequently, due to the great changes in nature and composition of the solid wastes into MSWI, the emission concentration of acid gas pollutants with high fluctuating conditions was occurred frequently. In order to realize the stability of the facility for controlling the acid gas pollutants, a full scale of MSWI in northern Taiwan, using semi-dry scrubbers to remove acid pollutants in the flue gas, was employed in this study. The effects of the operating variables, include type of chemicals, reaction temperature and stoichiometric ratio of chemical, on the removal efficiency of acid gas pollutants were investigated. Scenario simulation experiments were also carried out to understand the strategies for maintaining stability of the flue gas control system.
The results shown that when the flue gas at the temperature of 150 ℃ and using hydrate lime and sodium hydroxide as chemical agent at the stoichiometric ratio of excess dosing was 2.4 and 1.6, respectively, the HCl acid gas removal efficiency were both of over 96% and the SOx removal efficiency was above 86% and 78%, respectively. However, the increase of temperature of the flue gas, the HCI and SOx acid gas removal efficiency was gradually decreased. It also found that when the temperature of the flue gas increased to 210 ℃, only bicarbonate sodium at the stoichiometric chemical dosing ratio of 1.6, the HCl and SOx acid gas removal efficiency could be maintained above 96% and 85%, respectively.
In addition, the strategies for maintaining stability of the acid gas control system, the result of this study indicated that adding an extra cooling water spray system to control the temperature of flue gas approximately between 140 ~ 150 ℃ if at the necessary. So that the best acid gas removal efficiency could be obtained at the lowest stoichiometric dosing ratio of hydrate lime. Establish a new dry hydrated lime spray system for supplying the extra hydrate lime to enhance the removal efficiency of acid gases, when the exhaust gas emission concentration of acid gases suddenly changes. Besides, use crane to blend all kinds of solid wastes in the refuse bunker in order to make the nature of the feed into the waste incinerator maintaining at a uniform steady state at all operation time. |
