醫療用製氧機及平板型吸附塔製氧變壓吸附程序之研究

Study of Medical Oxygen Concentrater and Compact Flat-Box Adsorbers for Air Separation by PSA Processes

鄭智峰(Chih-Feng Cheng)

指導教授 ： 周正堂

國立中央大學/工學院/化學工程與材料工程學系/碩士(2007年)

摘要

變壓吸附程序一直以來都是使用圓柱型吸附塔來分離氣體，而本研究是利用相鄰的平板型吸附塔取代傳統的圓柱型吸附塔。一開始驗証程式是採用市售的圓柱塔製氧機程序，進料為20.762%的氧氣、0.938%的氬氣與78.300%的氮氣組成，吸附劑為採用UOP公司所生產的OXYSIV-5XPTM。其後，利用文獻上Skarstrom cycle程序的實驗數據來驗証程式的準確性，進料為21%的氧氣、79%的氮氣組成，吸附劑為5A沸石。模擬時所用的氣體分離機構為平衡模式，其假設吸附塔內的同一截面積上固、氣兩相瞬間達成平衡，且為非恆溫之變壓吸附模式，忽略吸附塔內的壓力降，而吸附平衡關係式皆採用extend Langmuir isotherms。
在驗証程式準確性後，利用相鄰的平板型吸附塔取代傳統的圓柱型吸附塔來進行模擬，由模擬結果可發現在相同的Purge to Feed Ratio與Product to Feed Ratio的情況下，平板型吸附塔條件下與圓柱型吸附塔並無太大差異，但平板型吸附塔比圓柱型吸附塔擁有更高的空間利用率。本研究並探討各操作變數(諸如：平板塔兩塔間的熱傳係數、各步驟操作時間、塔長、進料壓力)對模擬結果的影響。最後發現當進料壓力由4.26 atm降至3.26 atm時，平均進料流率由3.75 L/min降至2.88 L/min，雖產氣中氧氣純度已由原本的94.22 % 降至93.39 % ，但卻能省下可觀的pump秏電成本。

關鍵字

變壓吸附 ； 平板型吸附塔 ； 空氧分離

並列摘要

Cylindrical adsorbers are usually used for pressure swing adsorption (PSA) processes. In this study, the flat-box adsorbers which stack together replace the traditional cylindrical adsorbers. First, work was done to verify the applicability of the simulation program on the system of air (20.762% oxygen, 0.938% argon, and 78.300% nitrogen) separation with OXYSIV-5XPTM from UOP packed cylindrically in a commercialize oxygen generator. Another verification of the applicability of the simulation program was performed for separation of air (21% oxygen, and 79% nitrogen) with 5A zeolite in Skarstrom cycle. The latter simulation results was compared with the published experimental data. Instantaneous equilibrium between solid and gas phase with non-isothermal operation were assumed and the bed pressure drop could be neglected. The adsorption isotherms used were extend Langmuir isotherms.
After confirming the accuracy of the simulation program, the traditional cylindrical adsorbers were replaced by new compact flat-box adsorbers. The performance of the flat-box adsorbers was similar to that of the traditional cylindrical adsorbers at same purge to feed ratio and product to feed ratio. But the flat-box adsorbers was better than the cylindrical adsorbers in the usage rate of packing space. The effects of operating variables such as the heat transfer coefficient between neighboring adsorbers, step time, bed length, and adsorption pressure were investigated on the performance of PSA. Finally, as the feed pressure was reduced from 4.26 atm to 3.26 atm, the feed flow rate changed form 3.75 L/min to 2.88 L/min. A little price was paid: the oxygen purity in product was reduced from 94.22 % to 93.39 %, but less cost of electric power was used by pump.

並列關鍵字

pressure swing adsorption (PSA) ； flat-box adsorb

參考文獻

[1] Farooq, S., D. M. Ruthven, and H.A. Boniface, “Numerical Simulation of a Pressure Swing Adsorption Oxygen Unit”, Chem.Eng. Sci., Vol. 44, Iss. 12, 2809-2816, 1989

[2] Skarstrom,C.W., “Method and Apparatus for Fractionating Gaseous Mixtures by Adsorption”, U.S. Patent 2,944,627, assigned to Esso Research and Engineering Company, 1960

[4] Yang, R.T., and S.J. Doong, “Hydrogen Purification by The Multi-Bed Pressure Swing Adsorption Process”, Reactive Ploymers, Vol. 6, Iss.1, 7-13, 1987

[5] Marsh, W.D., F.S. Pramuk, R.C. Hoke,, and C.W. Skarstrom, “Pressure Equalization Depressuring in Heatless Adsorption”,U.S. Patent 3,142,547, assigned to Esso Research and Engineering Company, 1964

[6] Berlin, N.H., ”Method for Providing an Oxygen-Enriched Environment”, U.S. Patent 3,280,536, assigned to Esso Research and Engineering Company, 1966