D6.1 Definition of the BIONICO operating conditions and … · 2017. 11. 15. · Aspen Custom Modeler (ACM) [1], was used for the reactor design, as described in section 2.2. This

BIONICO

BIOGAS MEMBRANE REFORMER FOR DECENTRALIZED HYDROGEN PRODUCTION

FCH JU GRANT AGREEMENT NUMBER: 671459

Start date of project: 01/09/2015 Duration: 3.5 years

WP6 – Design and Manufacturing of novel biogas catalytic membrane reformer

D6.1 Definition of the BIONICO operating conditions and

performances Topic: FCH-02.2-2014 - Decentralized hydrogen production from clean CO2-containing biogas Type of Action: FCH2-RIA Research and Innovation action Call identifier: H2020-JTI-FCH-2014-1

Due date of deliverable:

2017-06-30

Actual submission date:

2017-10-30

Reference period:

2017-03-01 to 2018-07-31

Document name: BIONICO-WP6-D61-DLR-POLIMI-20171030-v2.docx

Prepared by (*): POLIMI

Version DATE Changes CHECKED APPROVED

V1 2017-08-07 First release POLIMI GDM

V2 2017-10-30 Results updates after partners’ inputs POLIMI GDM

Dissemination Level

PU Public X

PP Restricted to other programme participants (including the Commission Services)

RE Restricted to a group specified by the consortium (including the Commission Services)

CO Confidential, only for members of the consortium (including the Commission Services)

CON Confidential, only for members of the Consortium

___________________________________________________________________________________ (*) indicate the acronym of the partner that prepared the document


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Proj. Ref.: BIONICO - 671459 Doc. Ref.: BIONICO-WP6-D61-DLR-POLIMI-20171030-v2.docx Date: 2017/10/30 Page Nº: 2 of 24

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Content

EXECUTIVE SUMMARY ....................................................................................................................... 3

1 INTRODUCTION ............................................................................................................................ 4

2 METHODOLOGY ........................................................................................................................... 5

2.1 General assumptions and definitions ......................................................................................... 5

2.2 Fluidized bed autothermal membrane reactor model ................................................................ 7

2.3 System lay-out definition ............................................................................................................. 9

2.3.1 BIONICO lay-out using vacuum pump .............................................................................. 9

2.3.2 BIONICO lay-out using sweep gas ................................................................................... 10

3 RESULTS ...................................................................................................................................... 12

3.1 BIONICO system performance using vacuum pump ................................................................. 12

3.2 BIONICO system performance using sweep gas ....................................................................... 13

3.3 Results comparison ..................................................................................................................... 14

4 PRELIMINARY ECONOMIC ANALYSIS ....................................................................................... 16

4.1 Methodology ................................................................................................................................. 16

4.2 Economic Results ........................................................................................................................ 18

5 CONCLUSIONS ............................................................................................................................. 20

6 REFERENCES .............................................................................................................................. 21

7 ANNEXES ...................................................................................................................................... 23

7.1 Hydrodynamic parameters and mass and energy balance used in the phenomenological model ................................................................................................................................................... 23


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EXECUTIVE SUMMARY This work performed the techno-economic assessment of BIONICO plant, an innovative system for green hydrogen production from biogas based on autothermal fluidized bed membrane reactor. Performance in terms of hydrogen production efficiency and costs were assessed and compared to two conventional technologies for biogas processing in the context of hydrogen production: steam reforming and autothermal reforming. The former represents the most diffused system, while the second is closer to the technology developed within the BIONICO project. BIONICO system is expected to improve the efficiency of actual systems as well as reducing hydrogen production cost. Both biogas produced by landfill and anaerobic digestion are considered to assess the impact of biogas composition on system design. BIONICO system model is implemented in Aspen Plus and Aspen Custom Modeler to perform respectively the balance of plant with thermal integration and a detailed fluidized bed membrane reactor design. Two permeate side configurations, sweep gas and vacuum pump, were modelled and compared. The BIONICO system outperforms the reference cases by 10% points achieving a hydrogen production efficiency around 67-69% assuming a delivery pressure of 13.3 bara. In addition, the membrane reactor operates at lower temperature and pressure of the reference cases. Between the two permeate side configurations investigated, sweep gas and vacuum pump, the former is penalized by (i) the low hydrogen partial pressure in the feed side and (ii) the limited amount of sweep flowrate available. The resulting system efficiency and membrane for the sweep cases were 22% lower and two times larger than the vacuum pump ones. Afterwards, the preliminary economic assessment was carried out accounting for both the capital and operating costs to determine the hydrogen production costs. The hydrogen cost production of the BIONICO case ranges from 4.16 to 4.28 €/kgH2, while the reference case resulted 4.35 €/kgH2 and 4.48 €/kgH2 for the SR and ATR respectively. With respect to the steam reforming reference case, the BIONICO one has lower biogas and capital costs, but higher electricity costs (as consequence of the hydrogen compression consumptions), while it has lower biogas and electricity cost with respect to the ATR case. Between the landfill and anaerobic digestion cases, no big differences can be outlined.

SR ATR BIONICO

BG composition LF LF LF LF LF AD AD

Reactor temperature (°C) 800 800 550 550 550 550 550

Pfeed/Pperm 14 14 12/0.1 10/0.1 20/1.1 12/0.1 12/0.2

BG input (kW) 221 207 154.6 155.0 223.3 154.8 156.7

H2 production (kg/day) 100 100 100 100 100 100 100

System efficiency with H2 @ 1.02 bara

- - 71.51 71.90 55.36 72.99 73.83

System efficiency with H2 @ 13.3 bara

59.2 55.4 67.4 67.6 52.9 68.8 69.5

LCOH (€/kg) 4.35 4.48 4.17 4.28 5.15 4.16 4.27


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1 INTRODUCTION The current challenges of energy saving and reduction of CO2 emissions must deal with the significant growth of energy demand. Hydrogen is a promising energy carrier that can replace fossil fuels in power generation and transportation, drastically reducing local pollution and CO2 emission when produced by renewable sources. A less expensive way to produce hydrogen from biomass could be the adoption of biogas (BG) as a raw material for reforming processes: the conversion process can be similar to the steam reforming one, but for the smaller scale related to the BG production. BIONICO project focuses on the adoption of fluidized membrane reactor to produce green hydrogen from biogas to produce 100 kg/day of pure hydrogen. Membrane reactor allows the production and separation of hydrogen in a single reactor with advantages over traditional biogas reforming like an increase of the overall efficiency and strong decrease of volumes and footprint due to process intensification. This work performs a techno-economic assessment of BIONICO system through detailed modelling of the innovative system for two different biogas composition, defined in D2.1, where methane content is respectively 44% and 58%. Performance and hydrogen production cost are compared with results obtained in D2.2 for the two conventional technologies for biogas (BG) processing in the context of hydrogen production: steam reforming (SR) or autothermal reforming (ATR). The former represents the most diffused system, while the second is closer to the technology developed within the BIONICO project. In both cases, the reforming reactor is followed by two temperature-staged water gas shift reactors and a pressure swing adsorption system (PSA).


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2 METHODOLOGY 2.1 General assumptions and definitions The size of the considered hydrogen production plant is equal to the target of BIONICO project and equal to 100 kg/day with a purity of at least 4.0. The hydrogen is delivered at the same pressure for all cases at 13.3 bar. BG composition can vary significantly depending on the biomass raw material. To assess the impact of BG type on system design and performance, two different compositions are considered: the first BG is produced from landfill has a lower CH4 value and higher inert content, the second from anaerobic digester has a higher CH4 content resulting in the higher lower heating value. The two compositions are reported in Table 2.1.

Table 2.1 Investigated biogas compositions

Species units Landfill Anaerobic Digester

CH4

%mol

44.2 58.1

CO2 34.0 33.9

N2 16.0 3.8

O2 2.7 1.1

H2 0.0165 -

CO 0.0006 -

H2O Saturated Saturated

p, T bar, °C 1.013, 25 1.013, 25

LHV MJ/kg 12.7 17.8

The BG used in the model calculations is already exempt of sulphur content. Since BG from landfill contains sulphur compounds, a sulphur removal unit (e.g. based on active carbon) upstream the reforming system is required as it may poison both the reforming catalysts and the membrane. This step, that is prior to the inlet to the system, is not shown in the layout being neutral to the purpose of this model and common to the BIONICO configuration. Only sorbent replacement costs are included in the economic assessment. BIONICO system is modelled in Aspen Plus® [1], where mass and energy balances are solved. The methodology adopted is consistent with previous works [2–4]. The Peng-Robinson cubic equation of state [5] is used for all thermodynamic properties except for liquid molar volume evaluation where the Rackett model [6] is used and for steam properties where NBS/NRC steam tables [7] are adopted. A phenomenological model of a fluidized bed membrane reactor in the bubbling regime, developed in Aspen Custom Modeler (ACM) [1], was used for the reactor design, as described in section 2.2. This allows the integration of custom and standard components in Aspen Plus for simulations of complex chemical/energy systems. The importance of developing a phenomenological model of the membrane reactor implementing detailed transport phenomena in the membrane reactor was demonstrated in a previous work: the calculated membrane area of the detailed can be up to 50% higher than the one calculated with an ideal approach [8]. The design parameters and the main assumptions of the reference cases are summarized in Table 2.2. Auxiliary values adopted for the balance of plant (BoP) result from benchmark technologies, typical O&M specifications, requirements for the materials. The geometry adopted for the heat transfer corresponds to counter-current configuration with hot gas flow externally to staggered tube bundle and cold streams in tube. Such configuration provides compact design while keeping high heat transfer coefficient. The thermal dissipations are calculated directly given the geometrical and thermal design of each component plus 10% of heat losses to account for the manifolds and tubing connections of each component.


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The S/C ratio is controlled and fixed after the oxidation where the amount of water and methane is respectively higher and lower respect to the reactor inlet, while the O/C ratio, defined in Eq. (1), is manipulated in order to balance the heat required by the endothermic reforming reaction. The intake of air is obviously below stoichiometry, and regulated to control the reactor temperature.

𝑂 𝐶⁄ =2 ∙ 𝐹𝑂2

𝐹𝐶𝐻4

(1)

Another important parameter is the Hydrogen Recovery Factor (HRF) defined as the ratio between permeated hydrogen and the maximum amount of hydrogen that could be produced. It can be determined from the outlet streams of the reactor as follows:

𝐻𝑅𝐹 =𝐹𝐻2,𝑝𝑒𝑟𝑚

4 ∙ 𝐹𝐶𝐻4,𝑟𝑒𝑡 − 2𝐹𝑂2,𝑟𝑒𝑡 + 𝐹𝐶𝑂,𝑟𝑒𝑡 + 𝐹𝐻2,𝑟𝑒𝑡 + 𝐹𝐻2,𝑝𝑒𝑟𝑚 (2)

System performance at different operating conditions are compared in terms of overall efficiency, defined as the ratio of H2 energy output to biogas and auxiliaries energy inputs:

𝑠𝑦𝑠 =�̇�𝐻2

𝐿𝐻𝑉𝐻2

�̇�𝐵𝐺𝐿𝐻𝑉𝐵𝐺 +𝑊𝑎𝑢𝑥

𝑒𝑙,𝑟𝑒𝑓⁄

(3)

where:

𝐿𝐻𝑉𝐻2 is equal to 120 MJ/kg ;

𝑊𝑎𝑢𝑥 is the sum of the electric consumptions of the system auxiliaries (i.e. compressors, pumps, control system);

𝜂𝑒𝑙,𝑟𝑒𝑓 is set equal to 45%, as the average electric efficiency of the power generating park.

Table 2.2 Reference case model assumptions and design parameters

Parameter units valuea

Feed & operating conditions

Uniform Fluidized bed reforming temperature °C 550 (500-600)

Pressure reaction side bar 12 (8-16)

Pressure permeate side vacuum/sweep bar 0.1 (0.1-0.3) / 1.1

S/C ratio after oxidation - 3 (2.5-3.5)

u/umf at reactor inlet - 2.5 – 3.5

Excess air to burner % 100

λATR-MR (air to ATR-MR)b - ≈ 0.3

Sweep to CH4,BG ratio molar 1.5 - 2.5

Ambient temperature °C 15

Vented gas temperature °C 60

H2 production target kg/day 100

Heat Exchangers and thermal dissipations

Design minimum ∆T in exchangers gas/gas °C 30

Design minimum ∆T in exchangers gas/liquid °C 30


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Design minimum ∆T in exchangers liquid/bi-phase °C 15

Heat losses in HX’s and reactors piping and manifolds as % of calculated heat loss through walls:

% 10

Thermal conductivity insulating material for HX & ATR-MR @ T>400°C (ceramic fibre)

W/m.K 0.07

Thermal conductivity insulating material for HX & reactors @ T<400°C (glass fibre)

W/m.K 0.06

Insulation thickness ceramic fiber ATR-MR 25

Insulation thickness ceramic fiber HX & burner @T>400°C

cm 15

Insulation thickness glass fiber HX @T<400°C cm 5

Natural convection heat transfer coefficient W/m2.K 10

Auxiliaries & controls

Pumps hydraulic efficiency % 70

Pumps motor mechanical efficiency % 90

Compressors/fans isentropic efficiency % 70

Compressors/fans motor mechanical efficiency % 85

BG compressor maximum outlet temperature °C 120

Controller consumption (% of total auxiliary consumptions)

% 10

Vacuum pump

Isentropic efficiency % 70

Motor mechanical efficiency % 85

Inlet pressure bar 0.1 (0.1-0.2)

Discharge pressure bar 1.2

Maximum outlet temperature °C 70 a: Where a range of interest is shown between brackets, the most likely value is indicated separately b: Air to flow to ATR-MR is adjusted in order to control the temperature at the exit of the reactor

2.2 Fluidized bed autothermal membrane reactor model A phenomenological model of a fluidized bed membrane reactor in the bubbling regime, developed in Aspen Custom Modeler (ACM) [1], was used for the reactor design. Advantages of ACM are the fast coding (that allows a quick switch of the problem from design to simulation conditions by changing the “state” of the variables of the problem) and the computation of thermodynamic and transport properties of the species or mixtures by calling a large variety of internal sub-routines; main drawback is the poor control of the user on the solving procedure (e.g. there are no debug functions). The model includes reforming reactions (chemical equilibrium, different kinetic schemes), detailed hydrodynamics of bubble-emulsion phases, different options on the permeate side (vacuum or co-counter flow sweep gas, including gas diffusion limitations in the porous support). The bed is divided into three main regions, which lengths can be set by the user: the first region at the bottom of the reactor is dedicated to the oxidation and reforming reactions, the middle region is occupied by the membranes (permeation zones); the last section is a buffer region that mainly corresponds with the free-board region depending on the initial bed height and expansion. The schematic of ACM fluidized bed membrane reactor model is depicted in Figure 2.1.


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Figure 2.1 Scheme of fluidized bed membrane reactor developed in ACM for vacuum pump and sweep gas case

Correlations for the fluid-dynamic aspects of the bed are substantially the same as in the model developed by TU/e [8] (see also D5.5). The complete list of mass and energy balances, and fluid-dynamic equations for the bubbling bed are listed in Annex 23. Mass and energy balances are coded including the unsteady terms, but all the simulations here reported are performed only at steady-state. The schemes of reactions implemented are steam reforming (R.1), water gas shift (R.2) and methane oxidation (R.3), with kinetic laws from Trimm and Lam [9] and Numaguchi and Kikuchi [10] respectively.

CH4 + H2O <=> CO + 3 H2 ΔH298 K0 = 206 kJ/mol (R.1)

CO + H2O <=> CO2 + H2 ΔH298 K0 = -41 kJ/mol (R.2)

CH4 + 2 O2 => CO2 + 2 H2O ΔH298 K0 = -802 kJ/mol (R.3)

Solids can be distinguished between the catalyst and the filler material. The filler is chemically inert, made of the same material as the support of the catalyst. Only spherical particles with the nominal diameter are considered. Main features of reactor design are reported in Table 2.3.

Table 2.3 ACM membrane reactor parameters: geometry and catalyst

Parameter units value

L reactor m 1

L (from distributor to membrane)

m 0.1

D react m 0.45 - 0.6

Membr. distance m 0.015 – 0.025

The Aspen model includes also a global energy balance between the bed, the permeate stream, and the surroundings. The energy balance assumes a perfectly isothermal bed and energy transfer with the ambient is accounted for by heat conduction across the insulation thickness of the reactor and with the permeate side by heat conduction across the submerged membrane tubes and by the material flow of hydrogen.


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The membranes consist of a Pd-Ag layer (4.5 μm) deposited onto a ceramic multilayer porous support. Parameters of the permeation law (Eq. (4)) (permeability k0, permeance k0’, apparent activation energy Ea), listed in Table 2.4, comes from experimental analysis of D5.3. Hydrogen is assumed to be extracted from both the bubble and the emulsion phase, weighted on the local phase composition and extension of the two phases, as expressed in Eq. (33). Gas diffusion in the support is modelled by simplified Stefan-Maxwell equations (Eq. (32)) and affect results just for the sweep gas case: the pressure gradient is neglected and the effective gas diffusivity includes both the molecular and Knudsen diffusion contributions. The equations applied to a two-species mixture (hydrogen and the sweep gas) reduce to Fick’s law for non-stationary media and are then integrated for the specific case of cylindrical geometry.

�̇�𝐻2= 𝑘0 𝑒

−𝐸𝑎𝑅𝑇

(𝑃𝐻2,𝑓𝑒𝑒𝑑0.5 − 𝑃𝐻2,𝑝𝑒𝑟𝑚

0.5)

𝛿𝐴𝑚𝑒𝑚 = 𝑘0

′ 𝑒−𝐸𝑎𝑅𝑇 (𝑃𝐻2,𝑓𝑒𝑒𝑑

0.5 − 𝑃𝐻2,𝑝𝑒𝑟𝑚0.5)𝐴𝑚𝑒𝑚 (4)

Table 2.4 Membranes features

Parameter units value

OD/ID m 0.014/0.007

Support thickness m 0.0035

Length m 0.45

Membrane thickness

µm 4.5

k0 mol s-1 m-1 Pa-n 3.93 10-8

k0’ mol s-1 m-2 Pa-n 0.00874

k0’ (@ 550°C) mol s-1 m-2 Pa-n 0.00226

Ea kJ mol-1 9.26

n - 0.5

2.3 System lay-out definition This section presents two BIONICO system configurations which differ for the permeate side configuration. The first one assumes steam as sweep gas (i.e. reducing the hydrogen partial pressure) and the second one a vacuum pump at the permeate outlet (i.e. reducing the permeate total pressure). The adoption of sweep stream reduces auxiliaries’ power consumption increasing the complexity of the membrane reactor, while the vacuum pump is the opposite due to higher power consumption. In addition, sweep leads to a more homogeneous temperature inside the reactor because the steam helps the heat migration from the cold top end to the hot bottom end of the reactor. In the vacuum pump case, the reactor requires simpler constructive techniques and less welded joints (i.e. lower reactor costs and probably higher reliability), but infiltrations might occur in the plant section below atmospheric. 2.3.1 BIONICO lay-out using vacuum pump The vacuum pump configuration is shown in Figure 2.2. The BG is firstly compressed in CMPBG, then preheated up to 300°C in HX-4. At the inlet of the ATR-MR, it is mixed with steam and water. At the ATR-MR outlet, the retentate (point 3) and hydrogen (point 6) leave from the top section of the reactor. The separated hydrogen at close to atmospheric pressure is cooled to 30°C (thanks to the heat sink HXD-1), and then compressed to the delivery pressure by a vacuum pump. The retentate stream, which mainly consists of steam, CO2 and N2 with the remaining CO and H2 is cooled down to 200°C (point 4) where it is throttled before being combusted in air. The thermal power released during retentate and permeate cooling is used for steam production (HX-1, HX-2 and HX-3). The exhaust gases (point 5) are


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cooled down recovering water. The amount of hydrogen separated in the ATR-MR is determined so that the thermal power of the retentate close the energy balance of the system avoiding additional BG supply. Table 2.5 summarizes the thermodynamic properties of the main streams involved for one of the simulation case with landfill biogas.

Figure 2.2 Lay-out of BIONICO system using vacuum pump

Table 2.5 Vacuum pump case: stream properties at in/exit of reactors (@pressure and T)

Str

ea

m

Flow T

(°C) p

(bar)

Composition (% molar basis)

Molar (mol/s)

Mass (g/s)

CH4 H2 CO CO2 H2O O2 N2

1 0.44 12.25 282.6 12 44.2 - - 34.0 3.1 2.7 16

2 0.66 15.97 467 12 - - - - 43.6 11.8 44.6

3 0.82 27.1 550 12 0.05 0.9 0.41 0.9 12.6 - 44.6

4 0.82 27.1 230 12 0.05 0.9 0.41 0.9 12.6 - 44.6

5 0.99 32.07 312.7 1.1 - - - 34.8 11.3 2.9 51.0

6 0.58 1.17 550 0.1 - 100 - - - - -

2.3.2 BIONICO lay-out using sweep gas The same system with the adoption of sweep gas in the membrane reactor (sweep gas case) is depicted in Figure 2.3. With respect to the vacuum pump case, the lay-out is more complex because additional heat exchangers are required to evaporate the sweep gas steam (HX-6, HX-7, HX-8). Liquid feed water evaporated through HX-1 and HX-2 and finally superheated in HX-4 together with biogas. At the inlet of the reactor a preheated mix of compressed BG and steam (point 1) and compressed air (point 2) feed the reactor from the bottom section while steam for sweep gas is fed separately. At the outlet, the

Retentate

Exhaust

waterrec.

H2

BGfeed

AirATR

1 2

3

4

5

6

H2O

rea

ctio

n

P-1

CMPBG CMPair

Sep

ATR-MR

Sep

Burner

HX-2

Airbrn

Vac.P.

HX-4

HX-1

HX-3HXD-1

HXD-2


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retentate (point 3) and hydrogen (point 6) leave from the top section of the reactor. After cooling down, the remaining fuel in the retentate (point 4) is combusted in the burner for the steam generation. The sweep gas steam is evaporated thanks to the exhaust gas thermal power and superheated using the permeate stream. The process water is recycled from the condensation in all the three separators downstream the cooling of the permeate, retentate and exhaust gases. Table 2.6 summarizes the thermodynamic properties of the main streams involved for one of the simulation case with landfill biogas.

Figure 2.3 Lay-out of BIONICO system using sweep gas

Table 2.6 Sweep gas case: stream properties at in/exit of reactors (@pressure and T)

Str

ea

m

Flow T

(°C) p

(bar)

Composition (% molar basis)

Molar (mol/s)

Mass (g/s)

CH4 H2 CO CO2 H2O O2 N2

1 1.16 27.35 535 20 24.9 - - 19.2 45.4 1.5 9.0

2 0.32 9.32 520 20 - - - - - 21 79

3 1.24 35.51 550 20 6.4 5.4 2.0 32.9 24.3 - 29.1

4 0.9 28.29 30.1 20 8.6 7.4 2.7 41.1 0.2 - 39.9

5 2.32 70.76 335 1.1 - - - 20.2 9.6 4.7 65.5

6 1.15 11.56 550 1.1 - 50.0 - - 50.0 - -

P-1

H2Oreaction

CMPBG

waterrec.

BGfeed

P-2H2Osweep

CMPAir

AirATR

1 2

3

4

5

6

ATR-MR

HX-8

Sep

Burner

Airbrn

HX-7

XH-1

HX-6

HX-5

HX-3

HX-2

HX-4

Sep

HXD-1

H2

H2 + H2Osweep

Re

ten

tate

Exhaust

Sep


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3 RESULTS 3.1 BIONICO system performance using vacuum pump This section reports the system efficiency results for the BIONICO concept using both LF and AD biogas. Respect to the reference cases, the membrane reactor produces hydrogen at low pressure. Preliminary results are calculated assuming a H2 delivery pressure of 1.2 bara, and efficiency variation curve as function of the delivery pressure will be shown at the end of this section. Figure 3.1 and Figure 3.2 report the system efficiency for the vacuum pump case using LF BG and AD BG as feedstock respectively. In general, the BIONICO system can achieve hydrogen production efficiencies in the range of 73-74%. The highest efficiency is achieved when AD BG is used as feedstock thanks to the higher methane concentration.

Figure 3.1 BIONICO system performance using vacuum pump with LF BG

Figure 3.2 BIONICO system performance using vacuum pump with AD BG

The advantages of a higher CH4 concentration are more evident from the membrane surface area which reduces by 10% (3.5 m2 for LF BG vs. 3.17 m2 for AD BG) rather than system efficiency. In the same

500

600

2.53.5

0.210

14

68.5

69

69.5

70

70.5

71

71.5

72

72.5

2 3 4 5 6 7

Syst

em

eff

icie

ncy

(%

)

Membrane Area (m2)

T react S/C p vac p react

LF START12 bar, 550 °CS/C 3, 0.1 bar

500

600

2.5

3.5

0.210

14

71

71.5

72

72.5

73

73.5

74

2 3 4 5 6 7

Syst

em

eff

icie

ncy

(%

)

Membrane Area (m2)

T react S/C p vac p react

AD START12 bar, 550 °CS/C 3, 0.1 bar


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figure, the system efficiency and membrane surface area are determined for different reactor operating conditions. The following consideration can be drawn for both cases:

Reactor temperature reduction has negligible impact on the system efficiency thanks to the low heat required for self-sustaining reforming reactions, but it drastically affects the membrane surface area. At 500°C, membrane surface area increases by 85-90% mainly because of the lower hydrogen partial pressure in the feed side (less methane conversion). On the other hand, an increase of operating temperature (600°C) enhances permeance value and hydrogen production by reforming reaction reducing the required membrane area but also the hydrogen recovery factor (see Figure 3.3), thus system efficiency is lower. High dilution of hydrogen on the retentate side due to the increase of inert in the reactants streams (air for partial oxidation) has an high impact on LF BG respect to the AD BG where the methane concentration is higher.

The permeate pressure has a significant impact on the membrane area (and on system efficiency only for AD BG), while the feed pressure has limited impacts. Considering the opposite trends between the system efficiency and membrane area, the optimal operating condition will be identified using the economic assessment.

Regarding the S/C, reducing the steam (S/C 2.5), the membrane area increases because of the lower reactant concentration which penalizes product formation (H2). An opposite trend can be noticed for the two BG compositions as consequence of the different inert contents in BG stream. However, to prevent carbon deposition, the S/C ratio of 3 is considered the most interesting case.

Figure 3.3 Retentate hydrogen partial pressure (reactor exit) at different operating temperature

3.2 BIONICO system performance using sweep gas Results for the sweep case are reported in Figure 3.4 and Figure 3.5. The sweep gas case has lower performance and larger membrane area with respect to the vacuum pump case. The sweep gas pressure is set at 1.1 bar (slightly higher than the atmospheric pressure) leading to limited hydrogen partial pressure between the feed and the permeate side with the amount of sweep gas flowrate available. The gas diffusion in the porous support has a significant impact on the system efficiency where values above 50% can be obtained for higher pressure (16 - 20 bar) respect to the vacuum pump analysis (under 16 bar, system is not able to reach the BIONICO target). At high pressure, the benefits of higher hydrogen mass transfer in the support are larger than the increase of auxiliary consumptions. Figure 3.5 show as working at low sweep mass flow rate increases the pressure efficiency due to the less heat required for steam evaporation while decreasing the support thickness (from 3.5 mm to 2.0 mm) has advantages on system efficiency.

96.0

96.4

96.8

97.2

97.6

98.0

100

104

108

112

116

120

480 500 520 540 560 580 600 620

HR

F (%

)

H2

par

tial

pre

ssu

re (

mb

ar)

Temperature (°C)

LF AD HRF LF HRF AD


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Figure 3.4 BIONICO system performance using sweep gas

Figure 3.5 BIONICO system performance using different amount of sweep gas and different support thickness

3.3 Results comparison The impact of H2 delivery pressure on the system efficiency is reported in Figure 3.6. The H2 compression significantly affects the system efficiency with reduction around 5.7% points when H2 delivery pressure of 13.3 bara (consistent to the reference cases of D2.2) is considered. Anyway, the overall system efficiency for the BIONICO system is 67.8% which is 9% and 12% points higher than SMR and ATR cases assume as reference respectively.

20 19

18

17

53.0

53.5

54.0

54.5

55.0

55.5

56.0

7.0 7.5 8.0 8.5 9.0 9.5 10.0

Syst

em e

ffic

ien

cy (

%)

Membrane Area (m2)

LF BG550 °C , Sw/CH4 1.5

1.1 bar perm

44

46

48

50

52

54

56

58

15 16 17 18 19 20 21

Syst

em e

ffic

ien

cy (

%)

Pressure (bar)

t sup 3.5 t sup 3 t sup 2 Sw/CH4 2.5 Sw/CH4 2

LF BG550 °C, 7.84 m2

1.1 bar perm


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Figure 3.6 Example of H2 compressor consumption impact on BIONICO system efficiency

Finally, the power balances of the most interesting cases considered are summarized in Table 3.1.

Table 3.1 Power balances for the most interesting cases of the BIONICO system

Parameter units BIONICO LF BIONICO AD

Temperature °C 550 550 550 550 550

S/C - 3 3 3 3 3

P feed bar 12 10 20 12 12

P permeate Bar 0.1 0.1 1.1/sweep 0.1 0.2

BG Feed Nm3/h 35.2 35.3 50.8 26.8 27.1

BG Input kW 154.6 155.0 223.3 154.8 156.7

H2 production kg/day 100 100 100 100 100

H2 pressure delivery bar 1.2/13.3 1.2/13.3 1.2/13.3 1.2/13.3 1.2/13.3

System efficiency % 71.51 71.90 55.36 72.99 73.83

System efficiency with H2 compressor

% 67.4 67.6 52.9 68.8 69.5

BG compressor kW 4.5 4.3 7.4 3.4 3.5

Air compressor kW 4.9 4.7 4.1 5.3 5.3

H2 vacuum pump kW 6.4 6.4 - 6.4 6.4

H2 compressor kW 5.3 5.3 5.3 5.3 5.3

66%

67%

68%

69%

70%

71%

72%

73%

0 5 10 15 20 25

Syst

em e

ffic

ien

cy (

-)

H2 delivery pressure (bar)

LF BG550 °C, S/C 3

10 bar, 0.1 bar

No H2 compressor

1.2 13.3

Referencedelivery


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4 PRELIMINARY ECONOMIC ANALYSIS A preliminary economic analysis of BIONICO systems configurations is carried out to compare cost of produced hydrogen at different operating conditions. Results are also compared with values found for reference systems in D2.2. 4.1 Methodology Starting from the thermodynamic results, a preliminary economic analysis is developed to evaluate the hydrogen production cost (€/kg and €/Nm3) of the BIONICO concept. The methodology that has been used to perform this analysis is similar to previous ones on the same subject proposed by [11–13] that typically have an uncertainty of 30% due to limited cost data and design detail. Total plant costs (TPC) are calculated with the so-called bottom-up approach (BUA) which consists of breaking down the power plant into basic components or equipment, and adding installation and indirect costs. The first step consists of calculating the total direct plant costs (TDPC) which are the sum of the bare equipment costs and the corresponding installation costs (TIC) such as piping, erection, and outside battery limits. TDPC plus the indirect costs (IC), calculated as a percentage of the direct plant costs, leads to engineering, procurement and construction costs (EPC). Finally, TPC, which results from EPC plus owner’s cost and contingencies, is calculated. The individual installation costs are calculated as a percentage of the corresponding equipment one [14]. A rigorous methodology usually implies the adoption of dedicated coefficients for each item and plant component. However, this approach would require many arbitrary assumptions and could cause misleading results when applied to different, unconventional plants. For this reason and for sake of simplicity, they were assumed equal to 80% of the TDPC for the reference cases accordingly to previous studies of [12,14], and of 65% of the TDPC for the membrane reactor case due to the higher compactness and simplicity of the layout. Total plant costs aggregate and other coefficients adopted are shown in Errore. L'origine riferimento non è stata trovata..

Table 4.1 Methodology for the calculation of the Total Plant Cost [15]

Plant component Cost [k€]

Component W Component X Component Y Component Z Total Equipment Cost [TEC] Direct costs as percentage of [TEC] (includes piping/valves, civil works, instrumentation etc…)

A B C D

A+B+C+D

Total Installation Cost [TIC] Total Direct Plant Cost [TDPC] Indirect Cost [IC] Engineering, procurement and construction [EPC] Contingencies and owner’s costs (C&OC)

X% TEC TEC+TIC

14% TDPC TDPC+IC

Contingency Owner’s cost Total Contingencies&OC [C&OC] Total Plant Cost [TPC]

10% EPC 5% EPC 15% EPC

EPC+C&OC

The components cost figures have been obtained from several literature sources, vendor quotes and personal communication with experts. Since most these values are only valid for specific scales, it is common practice in engineering economics to select, for each component of the equipment, a scaling parameter. The actual erected cost C has been then derived from the cost C0 of a reference component of size S0 by the relationship:


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𝐶 = 𝐶0

𝑆

𝑆0

𝑓

(5)

where S is the actual size and f is the scale factor. Errore. L'origine riferimento non è stata trovata. summarize equipment costs and CEPCI value for all the components.

Components Scaling parameter S0 C0 (k€) f

SR Weight [lb] 130000 70.32 0.3

WGS Weight [lb] 130000 7.32 0.3

ATR Weight [lb] 130000 70.32 0.3

Heat exchanger Exchange area [m2] 2 15.5 0.59

Biogas compressor Power [kW] 5 3.3 0.82

Air compressor Power [MW] 0.68 3.42 0.67

Water demineralizer Water flowrate [lH2O/h] 90 2.1 0.68

Water pump Water flowrate [lH2O/h] 90 1.2 0.7

Hydrogen compressor Vacuum pump

Power [HP] 1 0.12 0.3

VSA unit Inlet flowrate [kmol/h] 17.069 27.95 0.6

Burner - - 5 -

The palladium membranes on the ceramic support cost are taken from previous project [16] and refers to a production at a semi-industrial scale. About ATR-MR reactor cost, reactor is considered as a pressurized vessel in T316 Stainless steel whose volume is a result of ACM model. The heat exchangers price corresponds to the type of the ones used in the Aspen Plus model: counter-current configuration with hot gas flow externally to staggered stainless steel tubes bundle. The exchange areas of the heat exchangers have been calculated starting from the temperatures and exchanged power calculated from Aspen Plus, using typical heat transfer coefficients for gas-gas, gas-liquid and liquid-biphase, which correspond to the one in Table 2.2. To evaluate the final cost of hydrogen, the consumables, auxiliaries and fixed costs must be added to the TPC, according to the following formulation:

𝐿𝐶𝑂𝐻 =(𝑇𝑃𝐶 ∗ 𝐶𝐶𝐹) + 𝐶𝑂&𝑚𝑓𝑖𝑥

+ (𝐶𝑜&𝑚𝑣𝑎𝑟∗ ℎ𝑒𝑞)

𝑘𝑔𝐻2(𝑜𝑟 𝑁𝑚𝐻2

3 ) (6)

where the operating hours of the plant have been taken equal to 7500, while the CCF have been taken equal to 15% (consistent with D2.2). Concerning the O&M fixed and variable, costs of consumables, auxiliaries, maintenance, insurance and labour are reported in Table 4.2. The cost of labour has been differentiated between the three cases analysed and accounts for two operators and refers to an average European rate, while catalyst price refers to BIONICO PGM catalyst and its quantity is defined by ACM model.

Table 4.2 O&M fixed and variable costs

Equipment Cost Lifetime (y)

Catalyst 831 [€/kg] 3

Deionasition Resin 447.07 [€/yr] 3


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Biogas LF 2.28 [€/GJ] -

Biogas AD 2.50 [€/GJ] -

Electric energy [17] 0.12 [€/kWh] -

Process water 0.35 [€/m3] -

Operation & Maintenance 3% TPC -

Labor cost 60000 € -

4.2 Economic Results The first step consisted in calculating the TEC and the TPC of the most interesting cases analysed, as reported in Table 4.3. All the cases consider a reactor temperature of 550°C and S/C of 3.

Table 4.3 Total Plant Cost of BIONICO layouts at different operating conditions

Cost (k€)

BG composition LF LF LF AD AD

Pfeed/Pperm 12/0.1 10/0.1 20/1.1 12/0.1 12/0.2

Reforming Reactor (and membrane)

24.2 28.6 49.7 21.8 33.6

Heat Exchangers 27.4 27.0 32.5 27.2 26.8

Biogas Compressor 3.2 3.1 4.7 2.5 2.6

Air Compressor/Fan 0.13 0.13 0.12 0.14 0.14

Water Demi + Pump 0.9 0.9 2.1 0.8 1.0

Vacuum Pump+ H2 compressor

10.7 10.7 4.9 10.7 9.3

Burner 5 5 5 5 5

TPC 150.0 158.1 207.8 143.2 164.5

Convenience of the BIONICO system from a TPC point of view depends on the biogas composition and on the operating conditions adopted, since the membrane cost has the largest influence on the total plant cost. The ATR-MR reactor configuration becomes convenient in terms of plant costs for high operating pressure and for AD biogas: this is because of the lower number of membrane required, due to the higher methane content in the biogas, while cost of the auxiliaries is limited. The overall cost of the hydrogen compressor used to bring the delivery pressure of hydrogen from 1.2 bar to 13.3 bar in the ATR-MR cases, have the same influence on TPC for all the MR-ATR cases, since the pressure ratio required is the same in all cases. Considering the different auxiliaries consumption and needs, the O&M variable costs were determined. Table 4.4 summarizes the singular contributes for the following cases.

Table 4.4 O&M variable costs of the different layouts considered

O&M costs (k€)

BG composition LF LF LF AD AD

Pfeed/Pperm case 12/0.1 10/0.1 20/1.1 12/0.1 12/0.2


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Catalyst cost 12.9 15.2 32.8 13.6 14.8

Biogas cost 9.5 9.5 13.7 10.4 10.6

Demi resin cost 0.45 0.45 0.45 0.45 0.45

Electric energy cost 20.4 20.1 16.4 19.7 18.1

Water cost 0.05 0.05 0.2 0.04 0.05

TOT 43.3 45.3 63.6 44.3 44.0

Using Eq. (6), the total costs of hydrogen have been calculated and reported in Table 4.5.

Table 4.5 Comparison of levelized cost of hydrogen between BIONICO system and reference system from D2.2

SR ATR BIONICO

BG composition LF LF LF LF LF AD AD

Pfeed/Pperm case - - 12/0.1 10/0.1 20/1.1 12/0.1 12/0.2

LCOH (€/kg) 4.35 4.48 4.17 4.28 5.15 4.16 4.27

LCOH (€/Nm3) 0.387 0.399 0.372 0.382 0.46 0.371 0.381

Within the accuracy of this analysis, the final hydrogen cost of the ATR conventional case is higher with respect to the SR case, due to the higher electric energy expenditure caused by the presence of the air compressor. Starting from the thermodynamic analysis performed in D2.2, costs of reference cases were updated according to the proposed methodology. The BIONICO concept seems to be cheaper with the reference system in all the cases using vacuum pump. When adopting AD biogas, the cost of hydrogen is lower than the one for the production by LF and a major impact can be noticed at 12 bar of retentate pressure. The major costs are the membrane reactor, therefore higher pressure are beneficial, and the variable O&M costs, due to the higher electricity consumption and catalyst cost. In general, when considering the economics of the different layouts studied, the membrane area needed is the main parameter that can determine the convenience of the system. For this reason, higher pressure in the retentate side should be preferred, even if the corresponding efficiency is slightly lower. Concerning the biogas composition, this short analysis showed how AD and LF are similar from an economic point of view: the first leads to a lower area of the membranes and to lower auxiliary electricity consumption, the second has a lower fuel cost and catalyst amount.


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5 CONCLUSIONS This work discussed a detailed techno-economic assessment of the innovative BIONICO system for hydrogen production from biogas. Performance of BIONICO concept is compared against two commercially available technologies based on reforming, water gas shift reactors and pressure swing adsorption for hydrogen purification defined in D2.2. The system simulations performed with Aspen considered two different biogas compositions, featuring typical landfill and anaerobic digestion cases, and two different permeate side configurations, vacuum pump and sweep gas, to assess the impact on overall system design, performance and costs. The BIONICO system outperforms the reference cases by 10% points achieving a hydrogen production efficiency around 67-69% assuming a delivery pressure of 13.3 bara. In addition, the membrane reactor operates at lower temperature and pressure of the reference cases. Between the two permeate side configurations investigated, sweep gas and vacuum pump, the former is penalized by the low hydrogen partial pressure in the feed side and the limited amount of sweep flowrate available. The resulting system efficiency and membrane for the sweep cases were 22% lower and two times larger than the vacuum pump ones. Afterwards, the preliminary economic assessment cases was carried out accounting for both the capital and operating costs to determine the hydrogen production costs. The hydrogen cost production of the BIONICO case ranges from 4.16 to 4.28 €/kgH2, while the reference case resulted 4.35 €/kgH2 and 4.48 €/kgH2 for the SR and ATR respectively. With respect to the steam reforming reference case, the BIONICO one has lower biogas and capital costs, but higher electricity costs (as consequence of the hydrogen compression consumptions), while it has lower biogas and electricity cost with respect to the ATR case. Between the landfill and anaerobic digestion cases, no big differences can be addressed.


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6 REFERENCES [1] AspenTech, Aspen Plus, (n.d.). http://www.aspentech.com/products/aspen-plus.aspx. [2] S. Foresti, G. Manzolini, Performances of a micro-CHP system fed with bio-ethanol based on

fluidized bed membrane reactor and PEM fuel cells, Int. J. Hydrogen Energy. 41 (2016) 9004–9021. doi:10.1016/j.ijhydene.2016.03.210.

[3] G. Di Marcoberardino, G. Manzolini, Investigation of a 5 kW micro-CHP PEM fuel cell based system integrated with membrane reactor under EU natural gas quality, Int. J. Hydrogen Energy. (2017).

[4] G. Di Marcoberardino, L. Roses, G. Manzolini, Technical assessment of a micro-cogeneration system based on polymer electrolyte membrane fuel cell and fluidized bed autothermal reformer, Appl. Energy. 162 (2016) 231–244. doi:10.1016/j.apenergy.2015.10.068.

[5] D.Y. Peng, D.B. Robinson, New two-constant equation of state, Ind Eng Chem Fundam. 15 (1976) 59–64.

[6] H.G. Rackett, Equation of state for saturated liquids, J. Chem. Eng. Data. 15 (1970) 514–517. http://www.scopus.com/inward/record.url?eid=2-s2.0-33947293984&partnerID=tZOtx3y1.

[7] L. Haar, J. Gallagher, G.S. Kell, NBS/NRC Steam Tables: Thermodynamic and Transport Properties and Computer Programs for Vapor and Liquid States of Water in S.I. Units., Hemisphere Publishing Corporation, Washington, 1984.

[8] G. Di Marcoberardino, F. Gallucci, G. Manzolini, M. van Sint Annaland, Definition of validated membrane reactor model for 5 kW power output CHP system for different natural gas compositions, Int. J. Hydrogen Energy. 41 (2016) 19141–19153. doi:10.1016/j.ijhydene.2016.07.102.

[9] L. Ma, D.L. Trimm, C. Jiang, The design and testing of an autothermal reactor for the conversion of light hydrocarbons to hydrogen I. The kinetics of the catalytic oxidation of light hydrocarbons, Appl. Catal. A Gen. 138 (1996) 275–283.

[10] K. Numaguchi, T, Kikuchi, Intrinsic kinetics and design simulation in a complex reaction network; steam-methane reforming., Chem. Enginnering Sci. 43 (1988) 2295 – 2301.

[11] M. Sjrdin, K. Damen, A. Faaij, Techno-economic prospects of small-scale membrane reactors in a future hydrogen-fuelled transportation sector, Energy. 31 (2006) 2523–2555. doi:10.1016/j.energy.2005.12.004.

[12] V. Spallina, D. Pandolfo, A. Battistella, M.C. Romano, M. Van Sint Annaland, F. Gallucci, Techno-economic assessment of membrane assisted fluidized bed reactors for pure H 2 production with CO 2 capture, Energy Convers. Manag. 120 (2016) 257–273. doi:10.1016/j.enconman.2016.04.073.

[13] L.B. Braga, J.L. Silveira, M.E. da Silva, C.E. Tuna, E.B. Machin, D.T. Pedroso, Hydrogen production by biogas steam reforming: A technical, economic and ecological analysis, Renew. Sustain. Energy Rev. 28 (2013) 166–173. doi:10.1016/j.rser.2013.07.060.

[14] G. Manzolini, E. Macchi, M. Gazzani, CO2 capture in natural gas combined cycle with SEWGS. Part B: Economic assessment, Int. J. Greenh. Gas Control. 12 (2013) 502–509. doi:10.1016/j.ijggc.2012.06.021.

[15] K. Gerdes, W.M. Summers, J. Wimer, Cost Estimation Methodology for NETL Assessments of Power Plant Performance DOE/NETL-2011/1455, (2011) 26. http://www.netl.doe.gov/File Library/research/energy analysis/publications/QGESSNETLCostEstMethod.pdf.

[16] FERRET, A flexible natural gas membrane reformer for m-CHP applications, (2014). http://www.ferret-h2.eu.

[17] European Commission, EuroStat, Statistics Explained, (2015). http://ec.europa.eu/eurostat/statistics-explained/index.php/Main_Page.

[18] D. Kunii, O. Levenspiel, Fluidization Engineering, Elsevier, 1991. doi:10.1016/B978-0-08-050664-7.50012-3.

[19] C.-Y. Shiau, C.-J. Lin, Equation for the superficial bubble-phase gas velocity in fluidized beds, AIChE J. 37 (1991) 953–954. doi:10.1002/aic.690370619.


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[20] S. Mori, C.Y. Wen, Estimation of bubble diameter in gaseous fluidized beds, AIChE J. 21 (1975) 109–115. doi:10.1002/aic.690210114.

[21] F. Gallucci, M. Van Sint Annaland, J.A.M. Kuipers, Autothermal Reforming of Methane with Integrated CO2 Capture in a Novel Fluidized Bed Membrane Reactor. Part 1: Experimental Demonstration, Top. Catal. 51 (2008) 133–145. doi:10.1007/s11244-008-9126-8.


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7 ANNEXES 7.1 Hydrodynamic parameters and mass and energy balance used in the phenomenological

model

Parameter Expressions Eq. Ref.

Archimedes number 𝐴𝑟 = 𝑑𝑝3𝜌𝑔(𝜌𝑝 − 𝜌𝑔)𝑔/𝜇𝑔

2 (7) [18]

Minimum fluidization velocity 𝑢𝑚𝑓 = (𝜇𝑔 𝑑𝑝𝜌𝑔⁄ ) (√(27.2)2 + 0.0408𝐴𝑟 − 27.2) (8) [19]

Bed voidage at minimum fluidization velocity

휀𝑚𝑓 = 0.586𝐴𝑟−0.029 (𝜌𝑔

𝜌𝑝

)

0.021

(9) [19]

Velocity of rise of swarm of bubbles

𝑢𝑏 = 𝑢𝑜 − 𝑢𝑚𝑓 + 𝑢𝑏𝑟 (10) [18]

Rising velocity of single bubble

𝑢𝑏𝑟 = 0.711(𝑔𝑑𝑏,𝑎𝑣𝑔)1/2 (11) [18]

Emulsion velocity 𝑢𝑒 =𝑢𝑜 − 𝛿𝑢𝑏

1 − 𝛿 (12) [18]

Average bubble diameter 𝑑𝑏,𝑎𝑣𝑔 = 𝑑𝑏,𝑚𝑎𝑥 − (𝑑𝑏,𝑚𝑎𝑥 − 𝑑𝑏𝑜)exp ( −0.3𝐻

𝐷𝑡) (13) [20]

Maximum bubble diameter 𝑑𝑏,𝑚𝑎𝑥 = 𝑚𝑖𝑛 (𝐷𝑥 , 0.65

𝜋

4𝐷𝑡

2(𝑢0 − 𝑢𝑚𝑓))

where 𝐷𝑥 = min (𝐷𝑡; 𝑑𝑖𝑠𝑡 𝑚𝑒𝑚)

(14) [20]

Initial bubble diameter 𝑑𝑏𝑜 = 0.376(𝑢𝑜 − 𝑢𝑚𝑓)2 (15) [21]

Bubble phase fraction 𝛿𝑏𝑛 =𝑢𝑏

𝑠

𝑢𝑏

(16) [21]

Emulsion phase fraction 𝛿𝑒𝑛 = 1 − 𝛿𝑏𝑛 (17) [21]

Maximum superficial bubble gas velocity

𝑢𝑠𝑏,𝑚𝑎𝑥 = 𝑢𝑜 − 𝑢𝑚𝑓 (18) [21]

Initial superficial bubble gas velocity

𝑢𝑠𝑏,𝑜 = 𝑢𝑏𝑟,𝑜𝛿𝑏𝑜

where 𝛿𝑏𝑜 = (1 − 𝐻𝑚𝑓 𝐻𝑓⁄ ) (19) [21]

Height of bed at minimum fluidization velocity

𝐻𝑚𝑓 = 𝐻𝑠

1 − 휀𝑠

1 − 휀𝑚𝑓

(20) [20]

Height of bed expansion

𝐻𝑓 = 𝐻𝑚𝑓𝐶1

𝐶1−𝐶2

where,

𝐶1 = 1 −𝑢𝑏,𝑜

𝑢𝑏,𝑎𝑣𝑔𝑒𝑥𝑝 (−

0.275

𝐷𝑇)

𝐶2 =𝑢𝑏

𝑠

𝑢𝑏,𝑎𝑣𝑔

[1 − 𝑒𝑥𝑝 (−0.275

𝐷𝑇

)]

(21)

(22)

(23)

[21]

Average bubble rise velocity 𝑢𝑏,𝑎𝑣𝑔 = 𝑢𝑜 − 𝑢𝑚𝑓 + 0.711(𝑔𝑑𝑏,𝑎𝑣𝑔)1/2 (24) [21]

Gas exchange coefficient

𝐾𝑏𝑐 = 4.5 (𝑢𝑚𝑓

𝑑𝑝) + 5.85 (

𝐷𝑔1/2𝑔1/4

𝑑𝑏5/4 )

𝐾𝑐𝑒 = 6.77 (𝐷𝑔𝜀𝑚𝑓𝑢𝑏

𝑑𝑏3 )

1/2

1

𝐾𝑏𝑒

= 1

𝐾𝑏𝑐

+ 1

𝐾𝑐𝑒

(25)

(26)

(27)

[21]


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Bubble-emulsion distribution, overall mass balance

𝛿 𝑢𝑏 + (1 − 𝛿)𝑢𝑒 = 1

𝑥𝑖,𝑟𝑒𝑡𝑢𝑟𝑒𝑡 = 𝑥𝑖,𝑏𝑢𝑏𝛿 + 𝑥𝑖,𝑒𝑢𝑒(1 − 𝛿)

(28)

Bubble mole balance 𝜕𝐶𝑖,𝑏

𝜕𝑡= −

𝜕(𝐶𝑖,𝑏𝑢𝑏)

𝜕𝑥− (𝐶𝑖,𝑏 − 𝐶𝑖,𝑒)𝛿𝐾𝑏𝑒 − 𝐹𝐻2,𝑏 (29)

Emulsion mole balance

𝜕𝐶𝑖,𝑒

𝜕𝑡= −

𝜕(𝐶𝑖,𝑒𝑢𝑒)

𝜕𝑥+ 𝑚𝑐𝑎𝑡 ∑ �̇�𝑟,𝑖

𝑁𝑅

𝑟

𝜐𝑟,𝑖

+ (𝐶𝑖,𝑏 − 𝐶𝑖,𝑒)𝛿𝐾𝑏𝑒 − 𝐹𝐻2,𝑒

(30)

Permeate mole balance 𝜕𝐶𝑖,𝑝𝑒𝑟

𝜕𝑡= −

𝑑(𝐶𝑖,𝑝𝑒𝑟𝑢𝑝𝑒𝑟)

𝑑𝑥+

𝐹𝐻2

𝛥𝑉𝑎𝑛𝑛𝑢𝑙𝑢𝑠 (31)

Gas diffusion in porous support

𝐶휀

𝜏

𝑑𝑥𝑖

𝑑𝛿𝑠𝑢𝑝= ∑

𝐹𝑗𝑥𝑖 − 𝐹𝑖𝑥𝑗

𝛥𝐴𝑚𝑒𝑚 𝐷𝑖𝑗𝑖≠𝑗

𝑥𝑠𝑢𝑝,𝑒𝑥𝑡 = (𝑥𝑠𝑢𝑝,𝑖𝑛𝑡 − 1) (𝑟𝑠𝑢𝑝,𝑒𝑥𝑡

𝑟𝑠𝑢𝑝,𝑖𝑛𝑡)

𝛼

+ 1

𝛼 =−𝐹𝐻2

𝜏 𝑟𝑠𝑢𝑝,𝑒𝑥𝑡

𝛥𝐴𝑚𝑒𝑚𝐶휀𝐷𝑖𝑗

1

𝐷𝑖𝑗=

1

𝐷𝑖𝑗𝑏𝑖𝑛

+1

𝐷𝑖𝐾𝑛𝑢

𝐷𝑖𝐾𝑛𝑢 =

2

3𝑟𝑝𝑜𝑟𝑒√

8𝑅𝑇

𝜋𝑀𝑊𝑖

(32)

Permeation law

𝐹𝐻2= 𝑘′0𝑒

−𝐸𝑎𝑅𝑇 𝛥𝐴𝑚𝑒𝑚 (((𝑃𝑥𝐻2

)𝑏

𝑛− (𝑃𝑥𝐻2

)𝑠𝑢𝑝,𝑒𝑥𝑡

𝑛) 𝛿

+ ((𝑃𝑥𝐻2)

𝑒

𝑛− (𝑃𝑥𝐻2

)𝑠𝑢𝑝,𝑒𝑥𝑡

𝑛) (1 − 𝛿))

(33)

Documents

D6.1 Definition of the BIONICO operating conditions and … · 2017. 11. 15. · Aspen Custom Modeler (ACM) [1], was used for the reactor design, as described in section 2.2. This