g10 physical & analytical chemistry assignment
DESCRIPTION
This is the assignment for absorption of CO2 using alkanolamineTRANSCRIPT
KKEK1135 PHYSICAL AND ANALYTICAL CHEMISTRY
SOLUBILITY OF ACID GASES IN AQUEOUS ALKANOLAMINES
ARISYA BINTI AHMAD ZAINI KEK150AZWAN BIN SHARI@DISIPELIHANNA SOFIA BINTI CHEK WIRAMAN KEKNURJAA BINTI ARIFFIN KEK150121NOR ANISA BINTI NASRUDIN KEKNUR AMANINA BINTI MOHD ARIEF KEK150120
GROUP 11
DEPARTMENT OF CHEMICAL ENGINEERINGUNIVERSITY OF MALAYA18 DECEMBER 2014
ABSTRACTAcid gas removal, or more commonly known as amine scrubbing, gas sweetening and acid gas removal, refers to a series of processes to remove acid gases such as hydrogen sulfide (HS) and carbon dioxide (CO) form gases in various industries using aqueous solutions of various alkylamines (or simply referred to as amines). This unit process is common in refineries, petrochemical plants and even natural gas processing plants. It is mainly to prevent corrosion and operational problems, as well as increasing heating value of the gas.Hydrogen sulfide needs to be removed as it is highly toxic and very poisonous, extremely corrosive with the presence of water and can cause catalyst poisoning in refinery vessels. As for carbon dioxide, it is removed as it has no heating value, corrosive with the presence of water and if the gas is heading to cryogenic plants, the presence of carbon dioxide may induce solidification. The most widely applied technology in the industry to facilitate the removal of these acid gases is by absorption and/or desorption process by aqueous alkanolamines as chemical solvents.Some of the different amines used in gas treating are: Diethanolamine (DEA) Monoethalamine (MEA) Methyldiethanolamine (MDEA) Triethanolamine (TEA) Aminomethyl propanol (AMP)This process of absorption is reflected by an acid-base mechanism. Hydrogen sulfide and carbon dioxide form weak acids in water or aqueous solutions, while the alkanolamines act as weak organic bases. When the sour gas stream is contacted with the aqueous alkanolamines solutions, the acid gas and the amine base react to form an acid-base complex, which is a salt. The process then follows up with the disposal or treating of the acid gas, and regenerating of amine solution for reuse.INTRODUCTIONThe acid gas under study in this topic is hydrogen sulphide. Hydrogen sulfide is a colorless gas with an offensive stench and is said to smell like rotten eggs.The gas can be detected at a level of 2 parts per billion. To put this into perspective, 1 mL of the gas distributed evenly in a 100-seat lecture hall is about 20ppb. Commercially hydrogen sulfide is obtained from "sour gas" natural gas wells.Hydrogen sulfide is used in chemicals industries to manufacture sodium sulfide and thiophenes, while in laboratory and analysis, is used to calibrate environmental emission monitoring, industrial hygiene monitors and trace impurity analyzers and as balance gas for some calibration mixtures.Acid Gas Partial Pressure : 1kPa, 10kPa, 30 kPa, 50kPa, 100kPa, 200kPa,500kPa, and 1000kPa.Absorption Temperature : 30C, 40C, 60C.
FIGURE 1 The apparatus for measuring the solubility of gases in water
CALCULATIONSThe system under study is the aqueous solution of Aminomethyl propanol associated with the acid gas hydrogen sulfide. The dissociation of Aminomethyl propanol in aqueous solution is given by equation of,(1)Other dissociations in the system are given by the equation below, (2) (3)(4)Charge neutrality for the system is given by the equation,(5)The mole balances involved in the system is reflected by the equation,(6)(7)Dissociation equations in the system : (8)(9)(10)(11)
To obtain the concentration of carbon dioxide soluble in the given amount of Aminomethyl propanol under specific pressure and temperature we use the Henry Laws equation, expressed in the form of,(12)By rearranging equation (8),
By rearranging equation (12),
By combining equation (9) and (12),
By the combination of (10), (11) and newly obtained equation for [],
From equation (11),
From all the above equations, we noticed that every other concentration can be calculated by calculating the concentration of H+ ions.From electroneutrality equation and the combination of newly derived equation , we can calculate the concentration of H+ ions.
The equation above is solve by the infamous method of Newton-Rhapson using the software Matlab and the goal seek method by using the software excelFrom mole balance of carbon dioxide, we obtained the solubility of carbon dioxide given by the equation,
Equilibrium constants for the system are calculated using the relationship below,For aminomethyl propanol : For first dissociation of carbon dioxide: For second dissociation of carbon dioxide: For water : Henry constant for carbon dioxide at various temperature is calculated using the relation given by,
Assumptions made during calculations : 1) Activity coefficient, is equal to 1
- 19 -
List of values and symbols: = 1, 10, 30, 50, 100, 200, 500, 1000 kPa = 1, 2, 3 and 4MP = PressureT = TemperatureKH = Henrys constant for carbon dioxideKW = Dissociation constant for waterKa = Dissociation constant for aminomethyl propanolKa1 = 1st dissociation constant for carbon dioxideKa2 = 2nd dissociation constant for carbon dioxideT = 303K, 313K, 333K
ResultsConcentration = 1MTemperature 303KPressure (kPa)[CO2][H][ HCO3 ][OH][CO32-][C4H11NOH]
10.1057570991.62378E-063.02E-023.15E-051.0056E-075.87E-020.13591324
101.0575709925.36612E-069.12E-029.54E-069.2077E-081.82E-011.14882125
303.1727129769.68037E-061.52E-015.29E-068.488E-083.05E-013.32446067
505.287854961.27613E-051.92E-014.01E-068.1405E-083.84E-015.47970794
10010.575709921.88488E-052.60E-012.72E-067.4628E-085.20E-0110.8354913
20021.151419842.83531E-053.45E-011.81E-066.5963E-086.91E-0121.4968184
50052.87854965.05089E-054.85E-011.01E-065.1964E-089.69E-0153.3632716
1000105.75709928.1393E-056.02E-016.29E-074.0022E-081.20E+00106.358693
Temperature 313KPressure (kPa)[CO2][H][ HCO3 ][OH][CO32-][C4H11NOH]
10.0867077831.56839E-062.78E-023.83E-059.2058E-085.48E-020.11446169
100.6408678895.17654E-068.41E-021.16E-056.246E-081.70E-010.95116458
301.9226036679.21017E-061.42E-016.51E-065.9193E-082.84E-012.7430146
503.2043394451.21498E-051.79E-014.94E-065.6691E-083.58E-014.51451717
1006.4086788891.7888E-052.43E-013.35E-065.2307E-084.86E-018.91411142
20012.817357782.67928E-053.25E-012.24E-064.6631E-086.50E-0117.6664755
50032.043394454.7363E-054.60E-011.27E-063.7305E-089.19E-0143.8133994
100064.086788897.56439E-055.75E-017.93E-072.9251E-081.15E+0087.2832081
Temperature 333KPressure (kPa)[CO2][H][ HCO3 ][OH][CO32-][C4H11NOH]
10.0640867891.3639E-062.46E-025.31E-058.3601E-084.77E-020.08866277
100.6408678894.50525E-067.44E-021.61E-057.6619E-081.49E-010.71526531
301.9226036678.0022E-061.26E-019.05E-067.2858E-082.51E-012.04826044
503.2043394451.05458E-051.59E-016.87E-066.9918E-083.18E-013.36325445
1006.4086788891.54514E-052.17E-014.69E-066.5139E-084.34E-016.6256011
20012.817357782.29694E-052.92E-013.15E-065.8953E-085.83E-0113.1092029
50032.043394454.00855E-054.18E-011.81E-064.8392E-088.36E-0132.4614689
100064.086788896.31318E-055.31E-011.15E-063.9019E-081.06E+0064.6177009
Graph of Solubility, , against Partial Pressure, P for 1M Amine
Concentration = 2MTemperature 303KPressure (kPa)[CO2][H][ HCO3 ][OH][CO32-][C4H11NOH]
10.1057570991.17136E-064.18E-024.37E-051.8272E-060.042694690.07378065
101.0575709923.74572E-061.31E-011.37E-051.7869E-060.130409170.59414829
303.1727129766.66453E-062.20E-017.68E-061.6933E-060.2208095131.69656509
505.287854968.74337E-062.80E-015.86E-061.6397E-060.2800415642.78393593
10010.575709921.27615E-053.84E-014.01E-061.5394E-060.3840270635.47970427
20021.151419841.88491E-055.20E-012.72E-061.4113E-060.51962376910.8354868
50052.87854963.24798E-057.54E-011.58E-061.1882E-060.75376853826.8161674
1000105.75709925.05106E-059.69E-011.01E-069.8264E-070.96939511753.3632552
Temperature 313KPressure (kPa)[CO2][H][ HCO3 ][OH][CO32-][C4H11NOH]
10.0867077831.11435E-064.39E-024.59E-052.0189E-060.0406591120.06288528
100.8670778353.59942E-061.36E-011.42E-051.9351E-060.1256354410.49400428
302.6012335056.36646E-062.31E-018.04E-061.8556E-060.2119804451.40317234
504.3353891758.34891E-062.93E-016.13E-061.7983E-060.2691074872.29803376
1008.670778351.21535E-054.03E-014.21E-061.6973E-060.3691062444.51446376
20017.34155671.79058E-055.47E-012.86E-061.5639E-060.5001223878.91386914
50043.353891753.06579E-057.99E-011.67E-061.3337E-060.7268534822.0318899
100086.70778354.73581E-051.03E+001.08E-061.1178E-060.93724506543.8134473
Temperature 333KPressure (kPa)[CO2][H][ HCO3 ][OH][CO32-][C4H11NOH]
10.0640867899.73293E-075.03E-025.26E-052.6465E-060.0356039760.04926322
100.6408678893.14855E-061.56E-011.63E-052.5289E-060.1107697560.37366188
301.9226036675.55655E-062.64E-019.21E-062.436E-060.1875421691.05178375
503.2043394457.27094E-063.37E-017.04E-062.3711E-060.238505241.71741514
1006.4086788891.05364E-054.65E-014.86E-062.2583E-060.3280500823.36339616
20012.817357781.54516E-056.34E-013.31E-062.1001E-060.4468899166.62559891
50032.043394452.61987E-059.35E-011.95E-061.8263E-060.65579724816.3415369
100064.086788894.00863E-051.22E+001.28E-061.5602E-060.85484346732.4614606
Graph of Solubility, , against Partial Pressure, P for 2M Amine
Concentration = 3MTemperature 303KPressure (kPa)[CO2][H][ HCO3 ][OH][CO32-][C4H11NOH]
10.1057570999.51947E-075.14E-025.38E-052.9258E-073.48E-020.05239904
101.0575709923.04215E-061.61E-011.68E-052.8649E-071.07E-010.40617695
303.1727129765.37893E-062.73E-019.52E-062.7492E-071.82E-011.14860392
505.287854967.04483E-063.48E-017.27E-062.6712E-072.32E-011.87846186
10010.575709921.02141E-054.79E-015.01E-062.5414E-073.20E-013.68503424
20021.151419841.49712E-056.54E-013.42E-062.3659E-074.36E-017.26851778
50052.87854962.54143E-059.63E-012.01E-062.0525E-076.42E-0117.9472987
1000105.75709923.88702E-051.26E+001.32E-061.7548E-078.40E-0135.6722735
Temperature 313KPressure (kPa)[CO2][H][ HCO3 ][OH][CO32-][C4H11NOH]
10.0867077839.14705E-074.76E-026.56E-052.7065E-073.23E-020.04476569
100.6408678892.91697E-061.49E-012.06E-051.9671E-079.95E-020.33876722
301.9226036675.14565E-062.54E-011.17E-051.8964E-071.69E-010.95166927
503.2043394456.72973E-063.23E-018.92E-061.8478E-072.16E-011.55292919
1006.4086788899.73647E-064.47E-016.16E-061.7655E-072.98E-013.03927848
20012.817357781.4249E-056.11E-014.21E-061.6487E-074.07E-015.98417067
50032.043394452.40614E-059.05E-012.49E-061.4455E-076.03E-0114.7527994
100064.086788893.66056E-051.19E+001.64E-061.2491E-077.93E-0129.298958
Temperature 333KPressure (kPa)[CO2][H][ HCO3 ][OH][CO32-][C4H11NOH]
10.0640867897.93942E-074.22E-029.12E-052.4672E-072.81E-020.03543569
100.6408678892.55713E-061.31E-012.83E-052.3783E-078.76E-020.25731523
301.9226036674.49578E-062.24E-011.61E-052.3083E-071.49E-010.71542202
503.2043394455.86935E-062.86E-011.23E-052.2572E-071.90E-011.1632906
1006.4086788898.47202E-063.96E-018.55E-062.1667E-072.64E-012.26810231
20012.817357781.23453E-055.43E-015.86E-062.0408E-073.62E-014.45345271
50032.043394452.06794E-058.10E-013.50E-061.8183E-075.41E-0110.9512674
100064.086788893.11721E-051.08E+002.32E-061.6005E-077.17E-0121.7206761
Graph of Solubility, , against Partial Pressure, P for 3M Amine
Concentration = 4MTemperature 303KPressure (kPa)[CO2][H][ HCO3 ][OH][CO32-][C4H11NOH]
10.1057570998.19813E-075.97E-026.25E-053.7302E-060.0300739610.04137212
101.0575709922.62854E-061.86E-011.95E-053.6285E-060.0933289990.31096464
303.1727129764.63294E-063.17E-011.11E-053.504E-060.1588446910.87244663
505.287854966.04762E-064.05E-018.47E-063.4274E-060.2024389141.42317285
10010.575709928.74387E-065.60E-015.86E-063.2791E-060.2800553042.78392794
20021.151419841.27616E-057.67E-014.01E-063.0788E-060.3840300385.47940243
50052.87854962.14477E-051.14E+002.39E-062.725E-060.57081540113.505015
1000105.75709923.24802E-051.51E+001.58E-062.3764E-060.75377446926.8161627
Temperature 313KPressure (kPa)[CO2][H][ HCO3 ][OH][CO32-][C4H11NOH]
10.0867077837.81476E-076.27E-026.55E-054.1052E-060.0286877520.03560273
100.8670778352.5197E-061.94E-012.03E-053.9488E-060.0896374950.25995754
302.6012335054.43498E-063.31E-011.15E-053.8238E-060.1525754030.72391838
504.3353891755.78644E-064.23E-018.85E-063.7438E-060.1945464691.17787698
1008.670778358.34893E-065.86E-016.13E-063.5967E-060.2691079682.29803349
20017.34155671.21535E-058.06E-014.21E-063.3946E-060.3691074014.51446307
50043.353891752.03407E-051.20E+002.52E-063.0297E-060.54944639811.1059628
100086.70778353.06583E-051.60E+001.67E-062.6673E-060.72685943322.0318853
Temperature 333KPressure (kPa)[CO2][H][ HCO3 ][OH][CO32-][C4H11NOH]
10.0640867896.92331E-077.07E-027.40E-055.2304E-060.0254569260.02812606
100.6408678892.205E-062.22E-012.32E-055.1564E-060.0788838660.19821977
301.9226036673.87408E-063.79E-011.32E-055.0112E-060.134577220.54553991
503.2043394455.05025E-064.85E-011.01E-054.9148E-060.1719228110.88404571
1006.4086788897.27092E-066.73E-017.04E-064.7422E-060.238504661.71741546
20012.817357781.05364E-059.29E-014.86E-064.5166E-060.3280497633.36339635
50032.043394451.75275E-051.40E+002.92E-064.0803E-060.4921562488.24988337
100064.086788892.6215E-051.87E+001.95E-063.648E-060.65607238416.3413373
Graph of Solubility, , against Partial Pressure, P for 4M Amine
Graph of Concentration of SpeciesVs Partial Pressure
T = 300CConcentration of Aminomethyl propanol = 4M
CONCLUSION
Based on the graph, the pattern of the graph shows the higher the temperature, the lower the solubility of carbon dioxide in aminomethyl propanol. The pattern of the graph also shows that when partial pressure of carbon dioxide increases, the solubility of carbon dioxide increases as well. From the graph of species concentration, when the concentration of amine increases, solubility decreases.
REFERENCE1. http://en.wikipedia.org/wiki/Carbon_dioxide2. http://en.wikipedia.org/wiki/Aminomethyl_propanol3. http://en.wikipedia.org/wiki/Henry's_law4. http://http://www.chemicalland21.com/specialtychem/nh/2-AMINO-2-METHYLPROPANOL.htm5. http://en.wikipedia.org/wiki/Amine_gas_treating6. A. Jahangiri , H. Pahlavanzadeh & A. Mohammadi (2014) The Modeling of CO2 Removal From a Gas Mixture by 2-amino-2-methyl-1-propanol (AMP) Using the Modified Kent Eisenberg Model, Petroleum Science and Technology, 32:9, 1104-1113