D5.1 Preliminary design of the lab scale membrane reactor

Transcription

BIONICO
BIOGAS MEMBRANE REFORME R FOR DECENTRALIZED HYDROGEN PRODUCTION
FCH JU G RANT A GREEMENT N UMBER : 671459
Start date of project: 01/09/2015
Duration: 3 years
WP5 – Lab Scale Biogas Reformer
D5.1 Preliminary Design of the Lab Scale Membrane Reactor
Topic:
Type of Action:
Call identifier:
FCH-02.2-2014 - Decentralized hydrogen production from clean CO2-containing biogas
FCH2-RIA Research and Innovation action
H2020-JTI-FCH-2014-1
Due date of deliverable:
2016-03-01
Actual submission date:
2016-04-21
Document name: BIONICO-WP5-D51-DLR-TuE-20160421-v01.doc
Reference period:
Prepared by (*):
TUE
Version
DATE
Changes
CHECKED
v0.1
2016-04-21
First release
TUE
APPROVED
Niek de
Nooijer
Dissemination Level
PU
Public
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
X
Confidential, only for members of the Consortium
___________________________________________________________________________________
(*) indicate the acronym of the partner that prepared the document
D5.1 Preliminary design of the
lab scale membrane reactor
Proj. Ref.: BIONICO - 671459
Doc. Ref.: BIONICO-WP5-D51-DLRTUE-20160421-v01
Date:
2016/04/21
Page Nº:
2 of 12
PUBLISHABLE SUMMARY
This deliverable reports the design of the lab scale membrane reactor. Particular attention is given to the
position and number of the membranes inside the reactor to improve the recovery and conversion.
_________________________________________________________________________________________________________________
PU
Date:
2016/04/21
Page Nº:
3 of 12
Content
PUBLISHABLE SUMMARY .................................................................................................................. 2
EXECUTIVE SUMMARY ....................................................................................................................... 4
1.1.
Description of the deliverable content and purpose .............................................................. 4
1.2.
Brief description of the state of the art and the innovation brought ....................................... 4
1.3.
Deviation from objectives ..................................................................................................... 4
1.4.
If relevant: corrective actions ............................................................................................... 4
1.5.
If relevant: Intellectual property rights .................................................................................. 4
LAB SCALE REACTOR DESIGN ......................................................................................................... 5
2.1.
The reactor .......................................................................................................................... 5
2.2.
The setup............................................................................................................................. 6
2.3.
Design model for biogas reforming ...................................................................................... 6
2.4.
Results design model........................................................................................................... 8
CONCLUSIONS .................................................................................................................................... 12
REFERENCES ...................................................................................................................................... 12
TABLE OF FIGURES
Errore. Il segnalibro non è definito.
_________________________________________________________________________________________________________________
PU
Date:
2016/04/21
Page Nº:
4 of 12
EXECUTIVE SUMMARY
1.1.
Description of the deliverable content and purpose
The deliverable reports on the preliminary design for the lab scale reactor for the reforming of biogas. The
lab scale reactor system will be placed in a setup used in prior projects with minor changes. In this design
a first model results are used to confirm the possibility for biogas reforming in the reactor. The model
parameters are varied to cover the possible range of operation for BIONICO.
1.2.
Brief description of the state of the art and the innovation brought
The design for the reactor for biogas reforming is presented. Beside this the design is validated with a
model and found to be suitable for biogas reforming with membranes.
1.3.
Deviation from objectives
Delivered few weeks after deadline to check the model results.
1.4.
If relevant: corrective actions
Not required.
1.5.
If relevant: Intellectual property rights
IP by TUE
_________________________________________________________________________________________________________________
PU
Date:
2016/04/21
Page Nº:
5 of 12
LAB SCALE REACTOR DESIGN
2.1.
The reactor
The reactor presented is selected for the integration of the BIONICO components. The length of the reactor
vessel allows operating it with different bed heights, Moreover different membrane lengths and
configurations also different space between the porous plate and the membranes to allow oxidation
reaction to convert all oxygen fed in case of autothermal reforming reactions. The reactor walls are made
of SS310 to be able to operate up to 600ºC. The porous plate, Inconel based with aperture of 40 microns,
can withstand higher temperatures to avoid damages in case of highly exothermic reactions taking place
at the entrance of the gas. The dimensions of the reactor is shown in Figure 1.
Figure 1 Reactor dimension in mm
The top flange of the reactor allows for the connection of five membranes via Swagelok connectors. With
the possibility for integration up to 10 pressure sensors or thermocouples. The membranes are connected
to the same permeate outlet, however can be opened and closed separately to allow separate
measurement or exclusion of a broken membrane. A picture of the flange is included in Figure 2.
Figure 2 Top flange of the reactor
_________________________________________________________________________________________________________________
PU
2.2.
Date:
2016/04/21
Page Nº:
6 of 12
The setup
Figure 3 shows a schematic representation of the setup. The setup is able to feed the required components
for a model biogas composition (only few MFC have been changed and recalibrated). The setup allows
for the extension to the integration of sweep gas on the permeate side. Both outlet from the reactor and
the permeate side can be analysed. The permeate flow is measured with the use of a bubble flow meter.
Figure 3 Scheme of the setup
2.3.
Design model for biogas reforming
To determine if the design allows for the desired operation parameters for the lab scale reactor a model is
made of the lab scale reactor. The model is used to predict the desired in flow regimes to have the
fluidization and composition range for the reactions. The model will also predict the expected outlet
composition where the analysers can be calibrated for. The model results can furthermore predict if
changes are required on the selected reactor or setup.
_________________________________________________________________________________________________________________
PU
Date:
2016/04/21
Page Nº:
7 of 12
Figure 4 Schematic representation of the gas in the model
The system is simulated with a typical fluidized bed model to describe the behaviour of a FBMR. The
model is based on the three phase model from Kunii and Levenspiel [1] to describe the gas and the solid
behaviour of the bed and combined with kinetics to describe the reaction system. The gas phase in the
model is divided into a bubble wake and emulsion fraction, a schematic representation is given in Figure
4. The mass transfer between bubble and emulsion is taken into account. The removal of hydrogen through
the membranes is modelled as a flux of hydrogen that is removed. For the flux is the following expression
used to estimate the flux JH2. Where Pm is the permeability of the membrane, tm the membrane layer
thickness and P0.5H2,ret
- P0.5H2,per.
𝑃𝑚 0.5
𝐽𝐻2 =
(𝑃
− 𝑃𝐻0.5
)
2 ,𝑝𝑒𝑟
𝑡𝑚 𝐻2 ,𝑟𝑒𝑡
The reactions in this model are based on the kinetics study of Numaguchi and Kikuchi [2], based on a
nickel catalyst, however in BIONICO is aimed to use an Rh based catalyst. The Rh catalyst is selected
over nickel due to its higher resistance to coke formation than nickel. Furthermore the activity of Rh is
much higher than the activity of nickel [3]. The exact kinetics for the BIONICO catalyst are however not
known yet. To accurately model the reactor these kinetics are required, experimental work is ongoing to
obtain the kinetics for the Rh catalyst used in BIONICO. For the design of the reactor the kinetics of
Numaguchi and Kikuchi are assumed to be comparable with the Rh catalyst. Because of the high loading
concentration of nickel used in the model. When the actual kinetic rate of the BIONICO catalyst is know
the design can be updated and checked if it is still suitable or if adaptations are required to the setup. The
DR reforming reaction is not included in the model of Numaguchi and Kikuchi. The DR reforming is
therefore assumed to have no significant effect on the design of the lab scale reactor and the CO2 is
assumed to be inert for the SMR reaction not for the WGS reaction.
The base case simulated for the design is formulated at possible lab scale conditions for the lab scale
reactor at TUE. For the base case normal Steam methane reforming is selected to obtain a case which
the Biogas case can be compared to. Furthermore the setup should be able to test the required biogas
compositions for the lab scale reactor. The base case and the biogas case are shown in table 1.
Properties
Pressure [bar]
Table 1 properties for simulation of Base cases
Base case Biogas
Base case SMR
reforming
4
4
_________________________________________________________________________________________________________________
PU
Temperature [K]
Bed height [m]
Reactor diameter [m]
u0/umf [-]
Steam/methane [-]
CH4 feed molar fraction [-]
H2O feed molar fraction [-]
CO2 feed molar fraction [-]
CO feed molar fraction [-]
H2 feed molar fraction [-]
N2 feed molar fraction [-]
Particle diameter [µm]
Solid density [kg/m 3]
Particle porosity [-]
Active phase content [wt%]
Sphericity factor [-]
2.4.
823
0.4
0.1
3
2.5
0.15
0.375
0.475
300
3650
0.404
20
0.75
Date:
2016/04/21
Page Nº:
8 of 12
823
0.4
0.1
3
2.5
0.15
0.375
0.115
0.36
300
3650
0.404
20
0.75
Results design model
First both base case systems are simulated and compared. In Figure 5 the conversion of both cases are
plotted. The Conversion of methane in biogas is lower compared to the normal SMR reaction case. This
can be explained due to the addition of CO2 in the feed stream. The CO2 is a product of the WGS reaction
therefore the reaction rate of the WGS is lowered and the equilibrium is reached faster for the WGS and
SMR resulting in a lower conversion.
Figure 5 Conversion and reaction rate of the SMR and biogas base case
_________________________________________________________________________________________________________________
PU
Date:
2016/04/21
Page Nº:
9 of 12
0,5
SMR CH4
Biogas CH4
Molar fraction [-]
0,4
SMR CO
Biogas CO
0,3
SMR CO2
0,2
Biogas CO2
SMR H2
0,1
Biogas H2
SMR H2O
0
0
0,08
0,16
0,24
0,32
0,4
Reactor lenght [m]
Biogas H2O
SMR N2
Figure 6 Composition in molar fraction over the length of the reactor
Figure 6 shows the composition in the reactor. The outlet compositions obtained when steam is condensed
is within range of the analyser available for both base cases. No effect of the outlet composition is obtained
on increase of the superficial velocity. The composition obtained at the outlet is at equilibrium for all cases.
Moreover it is mentioned before the BIONICO catalyst is expected to be equally active or even more active
the nickel simulated. Therefore there are not problems expected with obtaining equilibrium compositions
at the outlet.
To check the assumption that the dry reforming has no significant effect on the design of the lab scale
setup the kinetics in the model are adapted to include the dry reforming reaction. The rate of the dry
reforming reaction is assumed to be equal to the steam methane reforming. This assumption is the case
when the dissociation of methane on the catalyst surface is the kinetically limiting step [4]. Including the
DRR does not change the outlet conversion of methane or the outlet composition.
Molar fraction [-]
0,4
Biogas CH4
Biogas + DR
CH4
Biogas CO
0,3
Biogas + DR CO
0,2
Biogas CO2
Biogas + DR
CO2
Biogas H2
0,1
Biogas + DR H2
0
0
0,04
0,08
0,12
Reactor lenght [m]
Figure 7 the molar fraction along the beginning of the reactor for the biogas base case and the biogas case including dry
reforming.
_________________________________________________________________________________________________________________
PU
Date:
2016/04/21
Page Nº:
10 of 12
The membranes selectively remove hydrogen from the system. The selective removal of hydrogen shifts
the equilibrium of the WGS shift reaction. The shift in equilibrium results in a different outlet composition.
In the model the presence of the membranes is evaluated for both base cases and two different membrane
configurations. The two configurations are compared to evaluate the effect of the height of the membranes
in the reactor. In Figure 8 both reactor configurations are shown. In configuration A the membrane is 3 cm
from the distributor plate, in configuration B the membrane is 15 cm from the distributor plate. The
membrane selected represents the expected performance, the properties of the membrane are given in
Table 2.
Figure 8 Reactor configuration with membrane
Table 2 Membrane properties
Membrane Properties
Number of membranes
length [m]
Diameter [m]
Membrane thickness [m]
Reference permeability At Tref [mol1s-1m-1Pa0.5]
Activation energy [J/mol]
Permeate pressure [Pa]
PdAg membrane on ceramic support
5
0.17
0.01015
4*10-6
1.483*10-8
10.24*103
30397.5
Introduction of the membrane for both base cases increases the conversion significantly, as shown in
Figure 9. In Figure 9 the membrane configuration A is introduced. Removing the hydrogen shifts the
equilibrium resulting in much higher conversions. It must be noted that the conversion might be over
predicted since the model does not include concentration polarization. In the case of concentration
polarization the transport of hydrogen through the membrane is faster than the transport of hydrogen from
the bulk to the membrane wall.
_________________________________________________________________________________________________________________
PU
Date:
2016/04/21
Page Nº:
11 of 12
1
Conversion of CH4
0,8
0,6
0,4
Biogas
SMR
Biogas + Memb. A
SMR + Memb. A
0,2
0
0
0,1
0,2
0,3
0,4
Reactor lenght [m]
Figure 9 Conversion of CH4 for the base case with and without membranes
Figure 10 shows the conversion for membrane configuration A and B. The conversion is decreased when
the membranes are placed more upwards in the reactor. The effect for this decrease becomes clear when
the mass transfer limitations are removed (NML). In this case the concentration in the bubble wake and
emulsion phase are equal. The mass transfer limitations are more pronounced when the bubbles are big.
The bubble size increases from the bottom of the reactor to the top. The mass transfer is more enhanced
when the bubbles are small, therefore the conversion is higher when the membrane is placed near the
distributer where the mass transfer to the membrane is higher. It is thus suggested that also in the larger
scale reactor, the membranes should be placed closer to the bottom of the reactor.
1
Conversion of CH4
0,8
0,6
0,4
Biogas + Memb. A
Biogas + memb. B
Biogas + memb. B NML
0,2
0
0
0,1
0,2
0,3
0,4
Reactor lenght [m]
Figure 10 Conversion of methane for both membrane configurations and the effect of mass transfer limitations
From the results can be seen that the outlet composition changes significantly when the membranes are
introduced. Moreover the placement of the membrane can have an effect on the outlet composition.
Therefore it will be aimed at placing the membrane close to the distributor plate to avoid the mass transfer
limitation.
_________________________________________________________________________________________________________________
PU
Date:
2016/04/21
Page Nº:
12 of 12
CONCLUSIONS
The deliverable reports on the preliminary design for the lab scale reactor for the reforming of biogas. The
lab scale reactor system will be placed in a setup used in prior projects. In this design first model results
are used to confirm the possibility for biogas reforming in the reactor.
The results show that the reactor dimensions should be suitable for the system of BIONICO for biogas
reforming. However the model results are based on different kinetics. The results should be checked with
updated kinetics as soon as possible to review the possibility for biogas reforming in the setup. The effect
of dry reforming is not expected to effect the design significantly. The introduction of the membranes
changes the outlet composition significantly, however it is still within the range of the analyser.
REFERENCES
[1]
D. Rippin, Chemical reaction engineering O. Levenspiel Wiley. xv 501 pp. 81s, Chem. Eng. Sci.
19 (1964) 91.
[2]
T. Numaguchi, K. Kikuchi, Intrinsic kinetics and design simulation in a complex reaction network;
steam-methane reforming, Chem. Eng. Sci. 43 (1988) 2295–2301.
[3]
S.D. Angeli, G. Monteleone, A. Giaconia, A.A. Lemonidou, ScienceDirect State-of-the-art catalysts
for CH 4 steam reforming at low temperature, Int. J. Hydrogen Energy. 39 (2013) 1979–1997.
[4]
A. Donazzi, A. Beretta, G. Groppi, P. Forzatti, Catalytic partial oxidation of methane over a 4%
Rh/??-Al2O3 catalyst Part II: Role of CO2 reforming, J. Catal. 255 (2008) 259–268.
_________________________________________________________________________________________________________________
PU

D5.1 Preliminary design of the lab scale membrane reactor

Transcription

Similar documents

BIONICO - Biogas membrane reformer for decentralized H2 production

alkoxylation - Buss ChemTech

Keuzes voor electriciteitsopwekking

Structure of Cell Membranes (Insane in the membrane)

2014 Software Global Client Conference

Diffusion and Osmosis Worksheet