1 Introduction
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validate the column model for the operating conditions of interest,
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assess its predictive capacity,
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estimate important model parameters like transport coefficients based on experimental data,
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establish a suitable model for multi-component adsorption,
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demonstrate the technology at small-scale to pave the way towards a rapid advancement in technology readiness level.
2 Experimental
2.1 Materials
2.2 Experimental methods
2.2.1 Isotherm measurements
2.2.2 Breakthrough experiments
Parameter | Symbol [Unit] | Value |
---|---|---|
Particle diameter | \(d_{\text {p}}\) [m] | 0.0018 |
Skeletal density | \(\rho _{\text {s}}\) [kg/m3] | 2359 |
Particle density | \(\rho _{\text {p}}\) [kg/m3] | 1085 |
Bed density | \(\rho _{\text {b}}\) [kg/m3] | 595 |
Heat capacity of the sorbent | \(C_{\text {s}}\) [J/kg/K] | 1100 |
Inner column diameter | \(d_{\text {i}}\) [m] | 0.025 |
Outer column diameter | \(d_{\text {o}}\) [m] | 0.03 |
Column length | \(L_{\text {col}}\) [m] | 1.2 |
Heat capacity of the column wall | \(C_{\text {w}}\) [J/kg/K] | 4 × 106 |
Length of downstream piping | \(L_{\text {pipeD}}\) [m] | 10.51 |
Length of upstream piping | \(L_{\text {pipeU}}\) [m] | \(3.52^a\) |
\(2.84^{b}\) | ||
Diameter of piping | \(d_{\text {pipe}}\) [m] | \(0.006^{c}\) |
1 bar | 10 bar | 25 bar | |||
---|---|---|---|---|---|
CO2:CH4 = 50:50 | |||||
25 °C | 10 cm3/s | A2 | |||
20 cm3/s | A1 | A3 | A5 | ||
40 cm3/s | A4 | ||||
45 °C | 20 cm3/s | A6 | |||
65 °C | 20 cm3/s | A7 | |||
H2:CO2:CH4 = 75:20:5 | |||||
25 °C | 10 cm3/s | B2 | |||
20 cm3/s | B1 | B3 | B5 | ||
40 cm3/s | B4 | ||||
45 °C | 20 cm3/s | B6 | |||
65 °C | 20 cm3/s | B7 |
3 Modeling
3.1 Adsorption isotherms and heat of adsorption
3.1.1 Single component adsorption isotherms
3.1.2 Multi-component adsorption
3.2 Process modeling and estimation of transport coefficients
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the gas phase is described with the ideal gas law,
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the pressure drop is described with the Ergun equation (Eq. 20) ,
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diffusion is neglected [5],
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thermal equilibrium is reached between adsorbent particles and gas phase,
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axial conductivity of the column wall is neglected,
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mass transfer is described using a linear driving force (LDF) approximation,
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constant, average values are used for the heat of adsorption \(\Delta H_i^{\text {iso}}\), the heat capacity of wall \(C_\text {w}\), adsorbent \(C_\text {s}\), adsorbed phase \(C_\text {ads}\), and gas phase \(C_\text {g}\), the LDF coefficients \(k_i\) and the viscosity \(\mu\) of the gas phase.
3.2.1 Transport parameters and parameter estimation
4 Results
4.1 Adsorption isotherms
CH4 | H2 | CO2 | |||
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\(q^{\text{inf}}_i\) | \(A_{1,i}\) | mol/kg | 4.473 | 5.013 | 7.268 |
\(A_{2,i}\) | – | − 0.6569 | 0.0000 | − 0.6168 | |
\(b_i\) | \(B_{1,i}\) | \(10^{-4}\) bar\(^{-1}\) | 3.605 | 1.034 | 1.129 |
\(B_{2,i}\) | kJ/mol | 15.561 | 9.453 | 28.389 | |
\(s_i\) | \(C_{1,i}\) | – | 1.073 | 1.006 | 0.425 |
\(C_{2,i}\) | – | 0.0000 | 0.0000 | 0.7238 | |
\(T_{\text{ref}}\) | \(^{\circ }\)C | 25.0 | 25.0 | 25.0 |
4.1.1 Multi-component adsorption
4.2 Breakthrough experiments
4.2.1 Reference experiment and parameter estimation
CO2 | CH4 | H2 | ||
---|---|---|---|---|
\(k_{i}\) | \(\text{s}^{-1}\) | \(0.06^ {a}\) (\(0.09^{c}\)) | \(0.2^ {a}\) (\(0.4^ {c}\)) | \(1.0^ {b}\)(\(1.2^ {c}\)) |