Progress Towards a Comprehensive Model for Mass Transfer and Hydraulics for Structured Packings in Carbon Capture Service

Rate-based calculations theoretically offer more rigor and reliability for assessing column performance than the traditional equilibrium-stage approach. Unfortunately the rate-based method is ultimately tied to equipment performance correlations with limited predictive capability. We have undertaken an effort to develop significantly improved correlating expressions for mass transfer in columns containing sheet metal structured packings. To accomplish this, we have collected and simultaneously analyzed HETP data from 443 distillation experiments (Bennett, et al., 1992; Bravo, et al., 1985; Fitz, et al., 1999; Gualito, et al., 1997; and others) and 410 mass transfer area experiments (Tsai, 2010). The correlating expressions for the mass transfer performance for these sheet metal structured packings are shown below:

Sh_V = 0.333 Re_V¹ Sc_V¹ [cos(θ)/cos(Ï€/4)]^0.552

Sh_L = 0.1666Re_L^0.8 Sc_L^0.758 [cos(θ)/cos(π/4)]^0.747

a_m/a_d = 0.8093 Re_V^-0.0293 We_L^0.175 Fr_L^-0.1208

Sh_V = (k_yd_e/(c_VD_V))

Sh_L = (k_xd_e/(c_LD_L))

d_e = 4ε/a_d

The table below compares HETP predictions from the correlation above and from other popular mass transfer correlations in the open literature (Bravo, et al., 1985; Hanley and Chen, 2014; Wang, et al., 2016) with some of the experimental data we have collected. We find that the correlation of this work predicts the experimental HETP dataset with an average difference of 9.4% and a maximum difference of 50%; the next best correlation - that of Wang, et al. - predicts these same data with an average difference of 20% and a maximum difference of 172%.

			Pressure	Packing	Fs	HETP	This Work	Hanley & Chen	Wang, et al.	BRF85
Light Key	Heavy Key		Pa		Pa1/2	m	m	m	m	m
P-XYLENE	O-XYLENE		2000.0	Mellapak 250Y	0.8478	0.3615	0.4016	0.4318	0.4002	0.2549
P-XYLENE	O-XYLENE		13000.0	Mellapak 250Y	0.2332	0.3493	0.3587	0.3306	0.2851	0.2154
P-XYLENE	O-XYLENE		100000.0	Mellapak 250Y	0.2817	0.3221	0.3195	0.2677	0.2463	0.2303
IC4	NC4		690000.0	Mellapak 250Y	1.1402	0.2868	0.3061	0.2346	0.3007	0.3002
IC4	NC4		1140000.0	Mellapak 250Y	0.7191	0.2778	0.2773	0.2112	0.2525	0.2131
CYCLOC6	NC7		33000.0	Mellapak 250Y	3.1962	0.4111	0.4080	0.4068	0.4906	0.5029
CHLORBZ	ETHBZ		96000.0	Mellapak 250Y	1.5976	0.3548	0.3387	0.2698	0.3305	0.3636
CHLORBZ	ETHBZ		96000.0	Mellapak 350Y	2.0988	0.2631	0.2571	0.2204	0.2335	0.2671
CHLORBZ	ETHBZ		5000.0	Mellapak 500Y	1.0143	0.2195	0.2141	0.2443	0.1694	0.1196
2ME2BUTL	ISOBUTL		20000.0	Mellapak 500Y	1.2422	0.2805	0.2364	0.4578	0.2673	0.1584
2ME2BUTL	ISOBUTL		10000.0	Mellapak 500Y	1.1324	0.2694	0.2502	0.6447	0.3234	0.1488
2ME2BUTL	ISOBUTL		2000.0	Mellapak 500Y	1.6408	0.3365	0.2934	1.6509	0.5715	0.1538
CHLORBZ	ETHBZ		2000.0	Mellapak 500X	1.3943	0.2846	0.2811	0.7395	0.2240	0.1389
CHLORBZ	ETHBZ		10000.0	Mellapak 500X	1.3977	0.2780	0.2630	0.4882	0.1957	0.1578
CHLORBZ	ETHBZ		20000.0	Mellapak 500X	0.6351	0.2670	0.2490	0.4033	0.1654	0.1365
CHLORBZ	ETHBZ		95000.0	Mellapak 500X	1.9088	0.2434	0.2353	0.2651	0.1741	0.1931
2ME2BUTL	ISOBUTL		10000.0	Mellapak 500X	1.7589	0.3269	0.3225	2.2484	0.3967	0.1927
2ME2BUTL	ISOBUTL		20000.0	Mellapak 500X	1.3913	0.3035	0.2999	1.4575	0.3175	0.1865
2ME2BUTL	ISOBUTL		95000.0	Mellapak 500X	1.4372	0.2582	0.2609	0.5831	0.2208	0.1991
CHLORBZ	ETHBZ		10265.8	Mellapak 250Y	1.4602	0.3889	0.3810	0.3434	0.3772	0.3189
CHLORBZ	ETHBZ		10265.8	Mellapak 250Y	2.4386	0.3975	0.3883	0.3448	0.4072	0.3638
CHLORBZ	ETHBZ		10265.8	Mellapak 252Y	3.0246	0.4071	0.3918	0.3454	0.4208	0.3852
P-XYLENE	O-XYLENE		13332.2	Mellapak 252Y	2.9485	0.3553	0.3861	0.3363	0.4136	0.4035
CYCLOC6	NC7		165474.2	Mellapak 252Y	1.4631	0.3387	0.3479	0.3027	0.3624	0.3981
CYCLOC6	NC7		101325.0	Mellapak 752Y	1.7872	0.2271	0.2028	0.2164	0.1769	0.1943
ISOC8	TOLUENE		13332.2	ISP IT	1.4225	0.3105	0.3282	0.3567	0.3517
ISOC8	TOLUENE		13332.2	ISP 4T	1.3958	0.5555	0.6257	0.5648	0.8315
ARGON	OXYGEN		206842.7	Flexipac 500Y	0.9095	0.1811	0.1784	0.1586	0.1523	0.1533
P-XYLENE	O-XYLENE		5332.9	Flexipac 1.4X	2.5618	0.3454	0.3787	0.7143	0.3428	0.2802
P-XYLENE	O-XYLENE		26664.5	Flexipac 1.4X	2.2568	0.3493	0.3490	0.4606	0.3011	0.3037
P-XYLENE	O-XYLENE		159986.8	Flexipac 1.4X	1.5127	0.3150	0.3068	0.2799	0.2503	0.2824
P-XYLENE	O-XYLENE		439963.8	Flexipac 1.4X	1.4517	0.2731	0.2801	0.2105	0.2294	0.2549
P-XYLENE	O-XYLENE		5332.9	Flexipac 1.6X	1.2931	0.3531	0.4332	0.7964	0.3858
P-XYLENE	O-XYLENE		26664.5	Flexipac 1.6X	1.6225	0.3835	0.4043	0.5150	0.3551
P-XYLENE	O-XYLENE		159986.8	Flexipac 1.6X	1.1101	0.3581	0.3559	0.3131	0.2956
P-XYLENE	O-XYLENE		439963.8	Flexipac 1.6X	1.0491	0.3302	0.3247	0.2354	0.2699

In addition, we have used this new correlation to model the performance of several carbon capture pilot plant experiments reported in the literature (Gabrielson 2007 ; Notz et al., 2012) . Those results, along with results for the Bravo, Rocha Fair correlation of 1985 (Bravo, et al., 1985), the 2014 correlation of Hanley and Chen, and the 2016 correlation of Wang, et al., are summarized below. Again, the correlation of this work outperforms the other correlations examined.

Gabrielson Data

Run 1
	Experimental	This work	Wang	Hanley/Chen	BRF 85
Gas CO2 conc. Bottom (%vol)	2.62	2.62	2.62	2.62	2.62
Gas CO2 conc. Top (%vol)	1.69	1.645	1.602	1.089	1.278
Liquid CO2 loading top	0.072	0.07201	0.7201	0.07201	0.07201
Liquid CO2 loading bottom	0.178	0.183	0.1878	0.2451	0.224
Run 3
	Experimental	This work	Wang	Hanley/Chen	BRF 85
Gas CO2 conc. Bottom (%vol)	4.17	4.17	4.17	4.17	4.17
Gas CO2 conc. Top (%vol)	2.36	2.173	2.095	1.514	1.64
Liquid CO2 loading top	0.084	0.084	0.084	0.084	0.084
Liquid CO2 loading bottom	0.169	0.1789	0.1825	0.2093	0.2035
Run 6
	Experimental	This work	Wang	Hanley/Chen	BRF 85
Gas CO2 conc. Bottom (%vol)	4.58	4.58	4.58	4.58	4.58
Gas CO2 conc. Top (%vol)	2.9	2.883	2.785	2.142	2.337
Liquid CO2 loading top	0.147	0.147	0.147	0.147	0.147
Liquid CO2 loading bottom	0.226	0.2272	0.2318	0.2611	0.2523
Run 11
	Experimental	This work	Wang	Hanley/Chen	BRF 85
Gas CO2 conc. Bottom (%vol)	10.27	10.27	10.27	10.27	10.27
Gas CO2 conc. Top (%vol)	8.01	8.048	7.797	6.474	7.108
Liquid CO2 loading top	0.284	0.284	0.284	0.284	0.284
Liquid CO2 loading bottom	0.4	0.3945	0.4057	0.4663	0.438

Notz, et al., Experiment 2 Data

	Experimental	BRF85	Hanley/Chen	Wang	This work
GASOUT mflow (kg/hr)	65.6	66.3391	66.3941	66.6300	66.6127
GASOUT mfrac CO2	0.088	0.0750	0.0757	0.0795	0.0816
LEANIN mflow (kg/hr)	200	198.3004	198.3799	197.6807	197.6336
LEANIN molefrac (nCO2/nMEA)	0.308	0.2988	0.3022	0.2926	0.2899
RICHOUT mflow (kg/hr)	207.4	205.8422	205.9266	205.2253	205.1806
RICHOUT molefrac (nCO2/nMEA)	0.464	0.4692	0.4712	0.4553	0.4490
CO2OUT mflow (kg/hr)	6.14	7.0062	6.9543	6.6847	6.5384
CO2OUT mfrac CO2	0.996	0.9945	0.9945	0.9945	0.9945
WATERMU mflow (kg/hr)	1.21	1.4846	1.5416	1.7765	1.7660
RICHOUT HeatX duty (kW)	12.4036	11.9129	11.8712	11.9612	11.9935
LEANIN H2O (w/w)	0.653	0.6519	0.6514	0.6524	0.6526
LEANIN MEA (w/w)	0.284	0.2864	0.2863	0.2871	0.2873
LEANIN CO2 (w/w)	0.063	0.0617	0.0623	0.0605	0.0600

Future work will attempt to incorporate improved column hydraulic and pressure drop predictions to supplement the mass transfer correlation reported in this talk.

REFERENCES

Agrawal R, Woodward DW, Ludwig KA, Bennett DL. Impact of low pressure drop structure packing on air distillation. Paper presented at Distillation and Absorption: IChemE Symposium Series 128. Maastricht, The Netherlands, 1992.

Bravo JL, Rocha JA, Fair JR. Mass transfer in gauze packings. Hydrocarbon Process. 1985;64:91.

Chao Wang, Di Song, Frank A. Seibert, and Gary T. Rochelle. Dimensionless Models for Predicting the Effective Area, Liquid-Film, and Gas-Film Mass-Transfer Coefficients of Packing. Industrial & Engineering Chemistry Research. 2016 55 (18), 5373-5384

Fitz CW, Kunesh JG, Shariat A. Performance of structured packing in a commercial-scale column at pressures of 0.02–27.6 bar. Ind Eng Chem Res. 1999;38:512–518.

Gabrielsen J. CO2 capture from coal fired power plants. PhD Thesis, Technical University of Denmark, 2007.

Gualito JJ, Cerino FJ, Cardenas JC, Rocha JA. Design method for distillation columns filled with metallic, ceramic, or plastic structured packings. Ind Eng Chem Res. 1997;36:1747–1757.

Hanley B, Chen C-C. Letter to the Editor. AIChE J. 2012;58:132–152.

Notz, R., Mangalapally, H.P., Hoch, S., Hasse, H., 2011. Post combustion CO2 capture by reactive absorption: Pilot plant description and results of systematic studies with MEA. International Journal of Greenhouse Gas Control 6 (2012), 84-122.

Tsai, Robert E. Mass Transfer Area of Structured Packing. Ph.D. Dissertation. 2010.