| 摘要: | 碳捕獲與封存(Carbon Capture and Storage，簡稱CCS），是指收集如火力發電廠產生之二氧化碳，將它們儲存並長期與大氣隔離的技術過程。其中，吸附法為IPCC認為最有潛力且能夠放大至廠區規模等級操作的捕獲技術之一。
變壓吸附法是常用來分離氣體混合物的一種商業化技術，根據吸附劑對於混合氣體選擇性高低的不同，以及高壓時利於吸附劑吸附、低壓利於脫附之特性，來達到氣體分離的目的。
本研究以捕獲燃煤電廠所排放之煙道氣中二氧化碳為目的，以15%二氧化碳與85%氮氣作為進料，並選擇EIKME 13X作為本研究所使用之吸附劑，將之填入吸附塔進行突破及脫附實驗，並以此參數作為設計基礎，以利後續雙塔變壓吸附程序之實驗設計。本次實驗利用兩水準部分因子實驗設計，並以進料壓力、溫度、逆向減壓壓力、進料加壓/同相減壓時間、高壓吸附/逆相減壓時間作為操作變因，結果顯示，對純度及回收率而言，逆向減壓壓力皆為顯著因子。
由於逆向減壓壓力已達設備極限0.05 atm，在溫度338K的情況下，調整高壓吸附/逆相減壓時間為360秒，此時進料壓力為3.45 atm、進料加壓/同相減壓時間50秒，二氧化碳純度可達83.71%、回收率可達76.10%。
後續透過複迴歸分析，將數據進行迴歸，可以得到關於純度及回收率的迴歸模型，之後便能以此迴歸模型，對於製程的改良作判斷與決策。;Carbon capture and storage (CCS) is the process of capturing carbon dioxide (CO2) usually from large point sources, like coal-fired power plant, and depositing it where it will not enter the atmosphere. Among all the capture methods, IPCC thinks adsorption is the most potential capturing method and can be enlarged to the factory level.
Pressure swing adsorption process (PSA) is one of commercial technologies that are usually used to separate gas mixtures.According to the various selectivities of gas mixtures toward adsorbent, and based on the properties of adsorption at high pressure and desorption at low pressure, PSA uses these characteristics to achieve the target of gas separation.
This work presents a study for capturing carbon dioxide from dry flue gas (15% CO2 / 85% N2) emitted from coal-fired power plant using EIKME 13X as adsorbent.The breakthrough and desorption curves were discussed by changing different feed flow rate and temperature,and results were used to conduct the design of experiment of dual-bed PSA process. At this two-level fractional factorial design, parameter study was implemented to obtain a series of optimized settings of operating variables by investigating the effects of pressurization/cocurrent depressurization time, adsorption/countercurrent depressurization time, feed pressure, temperature, countercurrent depressurization pressure, and results show that the main effect of countercurrent depressurization pressure is significant for both CO2 purity and recovery.
As countercurrent depressurization pressure reaches the experimental lower limit of 0.05 atm, fixing temperature at 338K, feed pressure at 3.45 atm, pressurization/cocurrent depressurization time at 50s, then increasing adsorption/countercurrent depressurization time to 360 s, the process can get the CO2 purity of 83.71% and recovery of 76.10%.
Finally, by multiple regression analysis, we can get a regression model of CO2 purity and recovery, then via this model, we can make the decision of process improvement. |
