APPENDIX A
Significance of MON and RON
Ref.: http://www.refiningonline.com/engelhardkb/crep/TCR4_29.htm
For clarity it is useful to provide a general overview of an octane number. An octane number is a quantitative, but imprecise measure of the maximum compression ratio at which a particular fuel can be utilized in an engine without some of the fuel /air mixture "knocking" or self igniting. This self ignition of the air/fuel mixture in the cylinder results in a loss of peak power. Directionally as the compression ratio of the engine increases so does the required octane number of the gasoline if engine knocking is to be avoided. The performance of an engine is dependent upon many factors, one of which is the severity of operation. Accordingly the performance of a fuel is also dependent upon engine severity. To account for differences in the performance quality of a fuel two engine octane numbers are routinely used. The Research Octane Number (RON) simulates fuel performance under low severity engine operation. The Motor Octane Number (MON) simulates more severe operation that might be incurred at high speed or high load. In practice the octane of a gasoline is reported as the average of RON and MON or R+M/2.
Classically, both numbers are measured with a standardized single cylinder, variable compression ratio engine. For both RON and MON, the engine is operated at a constant speed (RPM's) and the compression ratio is increased until the onset of knocking. For RON engine speed is set at 600 rpm and MON is at 900 rpm.
MON and RON Depend on Gasoline Composition
The octane number measured is not an absolute number but rather a relative value based on accepted standards. By definition, n-heptane has an octane number (RON and MON) of 0, while iso-octane (2,2,4-trimethyl pentane) is 100. Linear combinations of these two components are used to measure the octane number of a particular fuel. A 90%/10% blend of iso-octane/n-heptane has an octane value of 90. Any fuel knocking at the same compression ratio as this mixture is said to have an octane number of 90. In general, RON values are never less than MON, although exceptions to this rule exist. For pure compounds the differences between RON and MON range from 0 to more than 15 numbers. Typical values for gasoline range hydrocarbons having boiling points between 30° and 350° F go from less than 0 to greater than 100 with the extreme values being generated by extrapolation. Table 1 summarizes actual RON and MON values for a variety of pure hydrocarbons.
In practice octane numbers do not blend linearly. To accommodate this, complex blending calculations employing blending octane numbers as opposed to the values for pure hydrocarbons are routinely employed. There is no universal blending program used industry wide. In fact, for a given oil company, blending calculations that are refinery specific are not uncommon. As an improvement over octane numbers of pure
Appendix - 2 compounds, there are tabulations of blending octane numbers for both RON and MON. Summarized in Table 1, these numbers are measured by blending 20 vol.% of the specific hydrocarbon in 80 vol.% of a 60/40 iso-octane/n-heptane mixture. Although still not exactly indicative of the actual blending octane number for a specific gasoline composition, the blending octane numbers are more representative. In general, the blending octane numbers are greater than the corresponding pure octane number.
APPENDIX B
Thermodynamic equilibrium
Figure B.1. Figure B.2.
C4 thermodynamic distribution C5 thermodynamic distribution
Figure B.3. Figure B.4.
Appendix - 4
APPENDIX C
Semi-developed and developed formulas of hydrocarbons
n-butane C4H10 CH3-CH2-CH2-CH3 isobutane C4H10 (CH3)2-CH-CH3 n-pentane C5H12 CH3-CH2-CH2-CH2-CH3 isopentane C5H12 (CH3)2-CH-CH2-CH3 2,2-dimehtylpropane C5H12 (CH3)3-C-CH3 n-hexane C6H14 CH3-CH2-CH2-CH2-CH2-CH3 2-methylpentane C6H14 (CH3)2-CH-CH2-CH2-CH3 3-methylpentane C6H14 CH3-CH2-CH(CH3)-CH2-CH3 2,2-dimethylbutane C6H14 (CH3)3-C-CH2-CH3 2,3-dimethylbutane C6H14 (CH3)2-CH-CH-(CH3)2 n-heptane C7H16 CH3-CH2-CH2-CH2-CH2-CH2-CH3 2-methylhexane C7H16 (CH3)2-CH-CH2-CH2-CH2-CH3 2,2-dimethylpentane C7H16 (CH3)3-C-CH2-CH2-CH3 Cyclomethylpentane C6H12 Cyclopentane C5H10 Cyclohexane C6H12 Cycloethylpentane C7H14 Cyclomethylhexane C7H14 Benzene C6H6 Toluene C7H8
CH3 | 1) CH3-CH2-CH2-CH3 =>CH-CH3 Hr=-9.19kJ/mol | CH3 CH3 | 2) CH3-CH2-CH2- CH2-CH3 => CH3-CH- CH2-CH3 Hr= -6.91kJ/mol CH3 | 3) CH3-CH2-CH2- CH2-CH3 => CH3-CH-CH3 Hr=-21.26kJ/mol | CH3 CH3 | 5) CH3-CH2-CH2- CH2-CH2-CH3 => CH3-CH2- CH- CH2-CH3 Hr= -5.03kJ/mol CH3 | 6) CH3-CH2-CH2- CH2-CH2-CH3 => CH3- CH- CH2-CH3 Hr= -17.67kJ/mol | CH3 CH3 | 7) CH3-CH2-CH2- CH2-CH2-CH3 => CH3- CH- CH-CH3 Hr= -9.81kJ/mol | CH3 CH3 | 4) CH3-CH2-CH2- CH2-CH2-CH3 => CH3-CH- CH2- CH2-CH3 Hr= -7.58kJ/mol
Appendix D
The ReactionsPURE COMPONENT PROPERTIES
Component Name Technological Data Medical Data Notes
Formula Mol. RON Boiling Boiling Melting Density Density T OC MAC LD50
Systematic Design Weight Point Point Point of Liquid of Liquid of ref. value Oral
Aspen (1) (1) Aspen (2) for (3)
g/mol oC oC oC kg/m3 kg/m3 density mg/m3 g Paraffins : n-butane n-butane C4H10 58.12 92 -0.11 -0.5 -135.0 573.2 573.0 600 658 i-butane i-butane C4H10 58.12 99 -11.3 -11.7 -145.0 551.7 551.0 (4) n-pentane n-pentane C5H12 72.15 62 36.5 36.1 -129.7 621.7 621.4 600 (4) i - pentane i - pentane C5H12 72.15 93 27.4 27.9 -160.0 616.3 614.6 (4) 2,2-dimethylpropane 2,2 DMProp C5H12 72.15 83 9.7 9.5 -16.6 585.4 585.1 120 (4) n-hexane n-hexane C6H14 86.17 29 68.9 68.7 -94.0 613.4 610.2 70.0 25 120 2-methylpentane 2 MP C6H14 86.17 78 60.7 60.3 -153.7 614.2 615.2 60.0 200 (4) 3-methylpentane 3 MP C6H14 86.17 76 63.5 63.3 / 628.2 626.3 60.0 200 (4) 2,2-dimethylbutane 2,2 DMB C6H14 86.17 92 50.3 49.7 -99.9 639.8 639.7 30.0 200 (4) 2,3-dimethylbutane 2,3 DMB C6H14 86.17 104 58.3 58.0 -128.5 624.1 624.3 60.0 200 (4) n-heptane n-heptane C7H16 100.20 0 98.4 98.4 -90.6 613.1 611.0 100.0 300 (4) 2-methylhexane 2 MH C7H16 100.20 42 89.9 90.1 -118.3 643.3 644.3 60.0 (4) 2,2-dimethylpentane 2,2 DMP C7H16 100.20 93 79.4 79.2 -123.8 622.5 621.5 80.0 (4) Naphtenes : cyclomethylpentane cMP C6H12 84.16 96 71.8 71.8 -142.5 744.5 743.9 95 (4) cyclohexane cyclohexane C6H12 84.16 84 80.8 80.7 6.5 773.1 773.9 250 (4) cyclopentane cyclopentane C5H10 72.15 102 49.5 49.3 -93.3 741.3 740.5 600 110 cycloethylpentane cEP C7H14 98.19 67 103.6 103.5 -138.5 762.6 762.2 (4) cyclomethylhexane cMH C7H14 98.19 75 103.6 100.9 -126.6 765.9 765.1 400 41 Aromatics : Benzene Benzene C6H6 78.11 106 815.23 80.1 5.5 815.2 813.4 80.0 1 1000 ppm Toluene Toluene C7H8 92.13 115 112.4 110.6 -95.0 780.9 783.8 110.0 40 5320 ppm Hydrogen Hydrogen H2 2.02 / -252.8 -259.2 / (4)
Notes (1) At 101.3 kPa. Selected values of physical properties of hydrocarbons and related compounds. Rossini
(2) Density at 25 oC, unless specified otherwise
(3) Oral in g/m3 for a mouse
APPENDIX F
TIP process
Figure C.1.: The paraffin Total Isomerisation Process
An economic evaluation of the TIP process has been realised by M.L.Maloncy (19) and the main results are presented in the table C.2.
Table C.2.: Economic evaluation of the IP process
Operating cost $189.42/ton
Hydrocarbon feed cost $150.38/ton
H-Mordenite $12.91/lb Zeolite 5A (pellets) $6.62/kg
Return of Investment 54%
Pay-out Time 2.5 years
Internal Rate of Return 43 %
Appendix - 8
APPENDIX G
Selectivities to isomerisation of n-pentane, n-hexane and n-heptane
APPENDIX AB
HAZOP for Option 2
Vessel – Double Membrane reactor
Intention – Separation of normal paraffins from dibranched and naphtene species to product and hydroisomerisation of normal paraffins
Guide Word
Deviation Possible causes Consequences Action required
No, Not NO TOP3 NAPHTHA FEED FLOW
(1) No naphtha available at
intermediate storage outside the battery limit. (2) Pump P101 fails. (3) Line blockage. (4) Line rupture. Loss of feed to reaction section. Reactor runs dry. Pump P101 overheats.
Loss of feed to reaction section. Reactor runs dry. As for (1).
As for (1), hydrocarbon discharged in industrial area.
(a) Ensure good communication with intermediate storage operator.
(b) Install low level alarm in the reactor. Covered by (b) (c) Install kickback on pump P101. Covered by (b). (d) Institute regular inspection and maintenance of piping. (e) Ensure adequate draining system.
NO H2 FLOW (5) No hydrogen feed
outside battery limits.
(6) Compressor K101 failure.
(7) Line blockage.
(8) Line rupture.
Loss of feed to reactor section. Increased cracking. Decrease in skeletal isomerisation. Temperature rises in reactor. As for (5). Hydrogen is discharged in industrial area. As for (5). As for (6). (f) Ensure good communication with operator outside battery limits. (g) Institute regular inspection and maintenance of the compressor. (h) Flow control on H2 streams <7>, <10>, <1> and <13>.
(i) Safety valve on purge stream to evacuate over-pressure vapours. (j) As for (d).
(k) Ensure adequate ventilation exists for enclosed work area.
Guide Word
Deviation Possible causes Consequences Action required
NO REACTOR EFFLUENT (9) Line blockage. (10) Line rupture. Pumps P102, P103 and compressor K101 overheat. As for (5). Discharge of H2 and hydrocarbons in industrial area. (l)Flow check on hydrocarbon and H2 streams: <4>, <14> and <5>.
(m) As for (e) and (f).
More MORE TOP3
NAPHTHA FEED FLOW
(11) Failure of flow controller.
Lower residence time in reactor, decrease in quality of product of isomerisation. (n) Regular inspection and maintenance of controller.
Backup flow controller. MORE
RECYCLE FLOW
(12) Decrease in the inner membrane efficiency.
Less flux through inner membrane. Flow in the recycle
increases.
(o) Institute regular regeneration of the membrane. (p) Flow control on recycle inlet, stream <9>. Relief bleed valve. MORE TEMPERATURE (13) Failure of TC of heat exchanger E101. Temperature rises in reactor. Increase in cracking. Decrease in high octane number species in product of isomerisation.
(q) Same as (n). Backup temperature controller.
MORE H2 FLOW (14) Failure of flow
controller on H2
make-up.
(15) Too much H2
recycle / too much compressing.
Higher reaction side pressure. Increased loss of H2 through
purge. Decreased flow through membrane. As for (14).
(r) Same as (n). Safety valve on purge stream to evacuate excess of hydrogen.
(s) Flow controller on H2
recycle after the compressor. Same as (r).
Less LESS TOP3
NAPHTHA FEED FLOW
(16) Failure of flow controller.
Higher residence time in reactor. Decrease in throughput. (t) Same as (n). LESS RECYCLE FLOW (17) Decrease in the feed side membrane efficiency.
Less flux through the feed side membrane. Decrease in
isomerised product from the feed. And from the recycle. Decrease in throughput.
(u) Institute regular regeneration of the membrane. LESS TEMPERATURE (18) Failure of TC of E101. Lower temperature in reactor. Decrease in activity of catalyst. Decrease in flow through the membrane. (v) Same as (n).
LESS H2 FLOW (19) Failure of flow
controller of hydrogen make-up. Decrease in H2 pressure in reactor. Increase in cracking. Decrease in skeletal isomerisation. (w) Same as (n).
Guide Word
Deviation Possible causes Consequences Action required
Other than MAINTENANCE (20) Equipment failure, regeneration of the membrane, regeneration of the catalyst. No production. Exposure to hydrogen gas and dust (catalyst) and heat.
(x) Safe work practices and/or appropriate personal protective equipment.
Part of WATER IN FEED
SULFUR IN FEED
(21) New feed: not dried.
(22) New feed: not desulfurised. Lower selectivity of the membrane. Blockage of pores of the membrane. Decrease in production. Catalyst poisoning. Catalyst poisoning.
(y) Ensure good communication with operators outside battery limits.
APPENDIX AB
FIRE AND EXPLOSION INDEX
AREA/COUNTRY DIVISION LOCATION DATE
The Netherlands - Rotterdam 21/01/2002
SITE MANUFACTURING UNIT PROCESS UNIT
Europoort Hydroisomerisation C4/C5/C6
PREPARED BY: APPROVED BY (Superintendent): BUILDING
CPD3267
REVIEWED BY (Management): REVIEWED BY (Technology center): REVIEWED BY (Safety and loss prevention):
Materials in process unit
Mixtures of paraffin : C4, C5, C6, C7, Benzene, Toluene.
State of operation Basic Materials for material factor Design - Start Up - Normal Operation - Shutdown Top3 (naphta)
Material Factor 21
1. General Process Hazards Penalty Factor Range Penalty Factor Used Base Factor………... 1.00 1.00
A. Exothermic Chemical Factors 0.30 to 1.25 0.30
B. Endothermic Processes 0.20 to 0.40 0.00
C. Material Handling and Transfer 0.25 to 1.05 0.85
D. Enclosed or indoor process units 0.25 to 0.90 0.00
E. Access 0.20 to 0.35 0.00
F. Drainage and spill control 0.25 to 0.50 0.00
General Process Hazards Factor (F1)……….. 2.15
2. Special Process Hazards
Base Factor………... 1.00 1.00
A. Toxic Materials 0.20 to 0.80 0.20
B. Sub-atmospheric Pressure (< 500 mm Hg) 0.5 0.00
C. Operation in or near Flammable Range _Inerted _Non inerted
1.Tank farms storage flammable Lliquids 0.5
2. Process Upset or purge failure 0.3
3. Always in flammable range 0.8 0.80
D. Dust explosion 0.25 to 2.00 0.00
E. Pressure Operating pressure 319 psig
Relief setting 435psig 0.47
F. Low temperature 0.20 to 0.30 0.00
G. Quantity of flammable/unstable material Quantity = 8714.75 kg
Hc = 1E04 kcal/kg 0.09
1. Liquids or gases in process
2. Liquids or gases in storage
3. Combustible solids in storage, dust in process
H. Corrosion and erosion 0.10 to 0.75 0.10
I. Leakage - Joints and packing 0.10 to 1.50 0.10
J. Use of fired equipment 0.00
K. Hot oil heat exchange system 0.15 to 1.15 0.00
L. Rotating equipment 0.5 0.00
Special Process Hazards Factor (F2)……….……….. 2.76 Process Unit Hazards Factor (F1 x F2) = F3……….. 5.9 Fire and Explosion Index (F3 x MF) = FEI…………...………...…...………... 125
APPENDIX O
Design of the reactor: scheme of both options
Legend : Reaction side with hydrogen
Feed side with branched paraffins that cannot go through the membrane.
SRN
Feed
Iso-alkanesH2 Outlet of recycle (iso-alkanes) (option 2)
First Pass Second Pass Separation of the reactor in two halves to make the fluid do two passes
Baffle
Recycle (option 2)
APPENDIX P
Calculation of the area of membrane needed (option 1 & 2)
The area of the membrane is the flow rate of species that are supposed to go through the membrane divided by the maximum flux through 1m2 of membrane.
Where the permeance is:
With = q / qsat where q = amount of adsorbed phase
qsat = maximum amount of adsorbed phase Parameters of the permeance.
p Pressure difference across the membrane 2 bars (3) Density of the membrane in kg/m3
2200 qsat (2) Concentration of adsorbed phase at saturation 13 g/gmembrane
D Corrected transport diffusivity See Table 8.1
in Percentage of adsorbed phase at the inlet of the membrane 0.999 (1) out Percentage of adsorbed phase at the outlet of the
membrane
0.99 (1)
Thickness of the membrane 3 micrometers
(1) These percentages have been chosen arbitrarily, assuming that the species adsorbed represent 99.9% of the maximum adsorbed quantity (qsat,) at their entrance of the
membrane, and 99% of the maximum adsorbed quantity when they leave the membrane. (2) Value found in [15].
(3) Value found in AiCHE Journal, Oct. 1997, Vol. 43, Number 10.
The diffusivities were found in [9] and adapted with a value found in [10]. They are presented in Table 8.1.
Hence, we calculate N for each specie: n-C4, n-C5, n-C6 and n-C7. With P = 2 bars.
(1
)
(1
)
(1
)
.
. .
.
. .
.
i out in sat satLn
Ln
Ln
N
q
D
q
D
p
p
p Thickness of membrane
.
Total Flow rate of normal alkanes
Total Flow rate of normal alkanes
Surface area
N
p
.
N
p
Specie n-C4 n-C5 n-C6 n-C7
Flow rate (mol/s) 6.421 53.748 7.845 0.0517
N (mol/s.m2) 0.1829 0.1179 0.0617 0.0298
Area of the membrane on SRN feed side (m2)
38.72 60.08 114.82 237 (4) Corrected Area (m2) (3) 48.40 75.10 143.53 - Total Area of the membrane on
SRN feed side (m2) 267.03
Area of the membrane on recycle side (m2) (OPTION 2)
11.07 17.18 32.84 67.9 (4) Corrected Area (m2) (3) 13.84 21.48 41.05 - Total Area of the membrane on
recycle side (m2) (OPTION 2) 76.40
Total Area (m2) (OPTION 2) 343.43
(4) The corrected area is the area multiplied by a correction factor 1.25 that compensates for the lack of accuracy of diffusivities values and for a lower efficiency of the membrane in practice.
(5) As the flowrate of n-C7 is very low compared with the other alkanes, and its diffusivity is also lower and increase a lot the area of the membrane, it was decided no to take n account n-C7 in the calculation of the area. It is then considered that n-C7 is not passing through the membrane and not isomerised. Hence, it does not participate to the increase in Ron value.
APPENDIX Q
Design of the reactor: Option 1 (no recycle)
1. Calculation of the catalyst volume needed
Characteristics of the catalyst AT-20
Loading density (kg/m3) 795 Particle diameter (mm) 1.4 Particle length (mm) 3-5
WHSV (h-1) 2
Mass flow rate of feed to the catalyst = 4.927 kg/s.
Catalyst weight = mass flow rate of feed / WHSV = 8868.96 kg. Catalyst bed volume = catalyst weight / density = 11.15 m3.
2. Comparability of catalyst and membrane performance: STY and ATY STY (space time yield) = reaction rate per unit volume of reactor
ATY (areal time yield) = permeation rate per unit area of membrane
In the hypothesis, the catalyst is very active. The reactants will be isomerised quickly after the membrane. Therefore, the flux through the membrane must be comparable to the rate of reaction on the catalyst. To compare them, the ration STY/ATY is a useful value that
indicates if the reactor is feasible or not.[13] Specie
considered Feed rate (mol/s)
%
converted(1) Reaction rate (mol/s)
n-C4 6.421 0.6926 4.447
n-C5 53.748 0.8633 46.401
n-C6 7.845 0.9167 7.191
n-C7 0.0517 0.9312 0.0482
(1) Calculated with the distribution at thermodynamic equilibrium (see Appendix B) Total reaction rate (incl. n-C7) Total reaction rate (excl. n-C7)
58.088 mol/s 58.039 mol/s
It was decided to design the membrane so that it provides a sufficient surface area for the exclusive passage of n-C4, n-C5, n-C6. Processing n-C7 in the catalyst bed provides an insignificant increase in the RON but requires a large additional membrane area because of its low flux through the membrane.
STY = Total reaction rate (excl. n-C7) / catalyst bed volume STY = 4.711 mol/m3.s
ATY = Flow through the membrane (excl. n-C7) / membrane area ATY = 0.255 mol/m2.s
STY / ATY = Area of tubes / Volume of catalyst = 4 / Dtube Dtube = 4 / 18.5 = 0.2162 m ~ 0.22 m
This is the minimum diameter to assure compatibility between the flux through the membrane and the capacity of the catalyst.
3. Geometry of the reactor 3.1. Length of the tubes Ltube
The length of tubes is fixed to be 3 m. 3.2. Number of tubes Ntube
Membrane area = 267.03 m2 = Ntube..Dtube.Ltube Ntube = 129 tubes. Catalyst volume = 12.32 m3 = Ntube..Dtube2.Ltube / 4 Ntube = 108 tubes.
Ntube = 129 tubes
3.3. Tubes Arrangement: triangular pitch Bundle diameter
From Coulson, Vol.6, Chap. 12, page 649, pt = 1.25 Dtube = 0.275 m.
K1 = 0.319 n1 = 2.142
Bundle diameter : Db = Dtube (Ntube / K1)1/n1 =3.62 m. Clearance and shell diameter
The clearance distance is taken to be 0.10 m. The diameter of the shell is then: Ds = Db + 2x0.10 = 3.82 m.
Baffles
These are needed in order to ensure a good mixing (an increased turbulence in the flow) in order to give sufficient contact time between the reactants and the membrane and allow therefore the separation of normals, isomers and aromatics to take place.
From an empirical rule applied for heat exchangers, the distance between 2 baffles is 0.2x shell diameter to 1x shell diameter. A distance of around 0.2x shell diameter has been chosen: 0.75 m, corresponding to 3 baffles.
Summary of dimensions
Vessel Diameter (m) 3.82
Tubes diameter (m) 0.22
Length of tubes (m) 3.00
Length of reactor (m) 3.50
Volume of catalyst per tube (m3) 0.0955 Height of catalyst per tube (m) 2.51
4. Hydrodynamics of the reactor Reynolds Number:
On the feed side:
as only half the area of the reactor is available for the fluid (see drawing in Appendix O: Design of the reactor; scheme of both options). Hence, Re = 5057. The flow is turbulent in the shell. Therefore, there is mixing in radial directions that favours the transfer of reactants through the membrane.
Pressure Drop:
In the packed bed:
Ergun’s equation was used to calculate the pressure drop in the packed bed:
Where: P is the pressure drop in Pa.
Porosity =volume of void/total volume of bed
0.38 Dp Diameter of particles (m) 0.0014 Viscosity of gas (Pa.s) 9.10-5 u Velocity of the gas (m/s) 8.79.10-3 Hence, P is equal to 504.5 Pa = 0.015 bars.
On the shell side:
As for the Reynolds number, calculations methods from heat exchangers have been applied for the pressure drop in the shell and recycle sides.
The pressure drop is composed of one longitudinal and one transversal pressure drop and depends on the number of baffles, n:
Where:
And:
3
4
Re
mass flowrate
with
0.17 10
Pa s and
.
mass flowrate
10.50
kg s
/
wet perimeter
_ 4 Re ( ) 2shell tubes outside tube
mass flowrate D N D
2 2 2 3 3 150 (1 ) . . 1.75 (1 ). . . . p p P u u L D D
( 1) L T P n P n P 2 L L L lG
mass flowrate
P
with
G
a
_
2 20.2
4
s outside tubesec
l tubes
free surface area
a
D
N
D
where
shell cross
tional area
0.2 2 _.
.
1.5
.
.
s T T T T L T L outside tubeD
h
G
P
N f
with
N
and
f
pt e
G
pt e
D
h is the free height above a baffle.
pt is the pitch (see 3.3.) and eL is the distance between the centre of one tube and the following line of tubes:
pitch pt
and:
Results First section of reactor Second section of reactor Total GL (kg/s) 6.439 (1) 4.738(1) PL (Pa) 0.08 0.04 0.12 GT (kg/s) 23.516(1) 17.299(1) PT (Pa) 3.22 1.82 5.04 P (Pa) 13.09 (2) 7.43 (2) 20.51 (2)
(1) W is varying from the entrance of the feed (10.50 kg/s) till the outlet (5.57 kg/s). For the calculation in each half of the reactor, an average was used between the inlet/outlet value and the average of both (10.50+5.57)/2.
(2) The number of baffles n is 3 in each section.
The final result is a pressure drop of 20.51 Pa, negligible compared to the 22 bar of the feed. In the first half of the reactor, the pressure decreases from 22 bars to 21.847 bars because of the pressure drop due to the baffles and the drop due to the height of the reactor (3m). In the second half, the pressure reaches again 22 bars because the fluid is now going from the top to the bottom of the reactor.
eL _
.
,
.
L outside tube T t s t Lpt e
D
mass flowrate
G
a
B D
a
pt e
APPENDIX R
Design of the reactor: Option 2 (with recycle)
1. Calculation of the catalyst volume needed
Characteristics of the catalyst AT-20
Loading density (kg/m3) 795 Particle diameter (mm) 1.4 Particle length (mm) 3-5
WHSV (h-1) 2
Mass flowrate of feed to the catalyst = fresh feed + recycle = 4.927+ 1.040 = 5.967 kg/s. Catalyst weight = mass flowrate of feed / WHSV = 10741.4 kg.
Catalyst bed volume = catalyst weight / density = 13.51 m3.
2. Comparability of catalyst and membrane performance: STY and ATY See Appendix Q: Design of the reactor: Option1 (no recycle).
3. Geometry of the reactor 3.1. Length of the tubes Ltube
The length of tubes is fixed to be 3 m. 3.2. Number of tubes Ntube
Membrane area on feed side = 267.03 m2 = Ntube..Doutside_tube.Ltube. Membrane area on recycle side = 76.40 m2 = Ntube..Dinside_tube.Ltube.
The inside diameter has been chosen as 0.07 m instead of 0.22/3 = 0.063 m in order to have an integer and because it is not possible to take 0.06 m, the area would not be sufficient. The outside diameter is then 0.23 m.
Ntube = 124 tubes
3.3. Tubes Arrangement: triangular pitch Bundle diameter
From Coulson, Vol.6, Chap. 12, page 649,
2 2
_ _
3 .( )
Catalyst volume = 13.51 m = .
4
outside tube inside tube tubes D D L N _ _
267.03
,
3.495
76.40
outside tube inside tubeD
Hence
D
pt = 1.25 Dtube = 0.2875 m is the pitch: distance between the centre of two adjacent tubes. K1 = 0.319
n1 = 2.142
Bundle diameter: Db = Dtube (Ntube / K1)1/n1 = 3.72 m. Clearance and shell diameter
The clearance distance is taken to be 0.10 m. Hence the shell diameter is: Ds = 3.73 + 2x0.10 = 3.92 m.
Baffles
These are needed in order to ensure a good mixing (an increased turbulence in the flow) in order to give sufficient contact time between the reactants and the membrane and allow therefore the separation of normals, isomers and aromatics to take place.
From an empirical rule applied for heat exchangers, the distance between 2 baffles is 0.2x shell diameter to 1x shell diameter. A distance of around 0.2x shell diameter has been chosen: 0.75 m, corresponding to 3 baffles.
Summary of dimensions
Vessel Diameter (m) 3.92
Tubes diameter (m) feed side 0.23 Tubes diameter (m) recycle side 0.07
Length of tubes (m) 3.00
Length of reactor (m) 3.50
Volume of catalyst per tube (m3) 0.1090 Height of catalyst per tube (m) 2.89
Number of baffles 3
4. Hydrodynamics of the reactor Reynolds Number:
On the feed side:
as only half the area of the reactor is available for the fluid (see drawing in Appendix O: Design of the reactor; scheme of both options). Hence, Re = 4848.
3
4
Re
mass flowrate
with
0.17 10
Pa s and
.
mass flowrate
10.50
kg s
/
wet perimeter
_ 4 Re ( ) 2shell tubes outside tube
mass flowrate D N D
On the recycle side:
Here, all the tubes are accessible to the recycle. Hence, Re = 13820.
On both retentate sides, feed and recycle sides, the flow is turbulent, it means there is mixing in radial directions that favours the transfer of reactants through the membrane.
Pressure Drop:
On the shell side:
See calculations in Appendix Q: Design of the reactor: Option 1.
In the packed bed:
Ergun’s equation was used to calculate the pressure drop in the packed bed:
Where: P is the pressure drop in Pa.
Porosity =volume of void/total volume of bed
0.38 Dp Diameter of particles (m) 0.0014 Viscosity of gas (Pa.s) 9.10-5
u Velocity of the gas (m/s) 0.0332
Hence, P is equal to 7203 Pa = 0.07 bars. _
4
Re 5.656 /
tubes inside tube
mass flowrate
with mass flowrate kg s
N D
2 2 2 3 3 150 (1 ) . . 1.75 (1 ). . . . p p P u u L D D
APPENDIX S
Design of the reactor: detail of option 2
Catalyst bed
Disc that isolates the outlet of the bigger tube from the shell
side Disc that isolates the outlet of the inner tube
from the outlet of the larger tube
H2 + products Iso of the recycle
Shell side outlet
Shell side inlet = SRN feed Hydrogen
inlet
APPENDIX T
Design of the Flash Vessel (option 2)
For the design of the flash vessel, the method for gravity settling in vertical vessel shown in Coulson, V.6 page 459is used.
Table T.1. Parameters of the calculation
Parameters of the calculation Value Remark
LIQUID DENSITY 424.88 kg/m3 (stream 8 ,see flow sheet) VAPOR DENSITY 39.28 kg/m3 (stream 7 ,see flow sheet) VAPOR VOLUMETRIC FLOW RATE 0.17 m3/s (stream 7 ,see flow sheet) LIQUID VOLUMETRIC FLOW RATE 0.01 m3/s (stream 8 ,see flow sheet)
SETTLING VELOCITY 0.22 m/s
MINIMUM VESSEL DIAMETER 0.98 m
MINIMUM VESSEL DIAMETE ROUNDED 2 m
HEIGHTS Height above the inlet (For Disengagement) 1.00 m
Height below the inlet (For Disengagement) 0.60 m Height For Liquid Hold Up (10 min) 2.54 m Height For Demister Pad 0.40 m
TOTAL HEIGHT 4.54 m
APPENDIX U
Flash: Choice of operating conditions
Temperature:
The sensitivity of the quality of the product as a function of the temperature has been considered. The RON value, the yield and the Reid vapour pressure were the parameters used to take a decision.
The temperature has not been increased above 120oC so as not to heat up the inlet of the flash.
The yield is the ratio flow rate of product/flow rate of feed x 100.
Option 1 (no recycle) Flow rate of feed = 10.50 kg/s.
T (oC) RON Flow rate of product (kg/s) Reid Vapor
Pressure (kPa) Yield (%)
30 86.98 10.501 88.90 100.01 35 86.98 10.501 88.90 100.01 50 86.98 10.501 88.95 100.01 60 86.98 10.500 89.03 100.01 75 86.98 10.500 89.03 100.00 85 86.99 10.498 89.00 99.98 100 87.02 10.490 89.00 99.90 120 87.21 10.424 88.75 99.28
Option 2 (with recycle) Flow rate of feed = 10.50 kg/s.
T (oC) RON Flow rate of product
(kg/s)
Reid Vapor
Pressure (kPa) Yield (%)
30 88.43 10.490 89.63 99.91 35 88.43 10.488 89.55 99.89 50 88.43 10.479 89.55 99.80 60 88.43 10.471 89.48 99.73 75 88.42 10.452 89.40 99.54 85 88.42 10.431 89.33 99.34 100 88.41 10.376 89.03 98.83 120 88.39 10.178 88.13 96.93
It was decided to operate at 120oC to avoid any expense in cooling down or heating up the fluid and also because there is no benefit in the RON in changing the temperature.
Pressure:
A decrease in pressure is also not interesting because more product is lost in the purge and the quality of the final product is decreased.
APPENDIX V
REACTORS & VESSELS
–
SUMMARY
EQUIPMENT NR. :
NAME :
R101 Double Membrane Reactor for
Hydroisomerisation
V101
Flash Vessel
Reactor Vertical
Pressure [bara] :
- shell side
- packed bed
22
20
19.5
Temp.
[
oC]
- Inlet feed :
- Outlet product :
90.0
121.0
120.0
120.0
Volume [m
3]
:
Diameter [m]
:
L or H
[m]
:
3.92
3.00
14.45
2.0
4.6
Internals
- Catalyst
Type
:
Shape
:
- Tubes
Type :
Diameter[m] :
Number :
Chlorided Alumina with Platinum
Cylindrical particles
Membrane coated on SS.
0.23 & 0.07
124 x 2.
n.a.
n.a.
n.a.
n.a.
n.a.
Number
-
Series
:
- Parallel
:
1
-
1
-
Materials of
Construction
(1) :
Shell: CS
Tubes: SS + zeolite 5A
CS
Other
: Baffles
Remarks:
(1) SS = Stainless Steel; CS = Carbon Steel
Designers : J.A.M Arnaud
E.E. McLeary
M. Tanfour K. T. Wudie
Project ID-Number : CPD3267
APPENDIX V
REACTOR– SPECIFICATION SHEET
EQUIPMENT NUMBER : R-101 In Series : 1 NAME : Double Membrane Reactor for Hydroisomerisation In Parallel : none
General Data
Service : - Buffer / Storage / Separation / Hydroisomeriser
Type : - Packed Bed
- Double Tubular membranes
Position : - Horizontal
- Vertical
Internals : - Demister / Plate / Coil / Tube bundle
Heating/Cooling medium : - none / Open / Closed / External Hxgr /________ - Type : n.a.
- Quantity [kg/s] : n.a. - Press./Temp.’s [bara/oC] : n.a.
Vessel Diameter (ID) [m] : 3.92 Number of tubes : 125 Vessel Tot. Volume [m3] : 36.2 Tube diameters [m] : 0.07 / 0.22
Vessel Height [m] : 3.50 Tube length [m] : 3.00 Vessel Material : CS Tube Material : Zeolite 5A on metal
Other : 3 Baffles
Process Conditions
Stream Data
Feed Hydrogenrecycle
Recycle Outlet Shell side Outlet recycle Outlet catalyst bed Temperature [oC] Pressure [bara] Density [kg/m3] Mass Flow [kg/s] : 90 : 22 : 516.7 : 10.500 : 120.6 : 20 : 39.7 : 6.165 : 120 : 22 : 426.6 : 5.646 : 90 : 22 : 530.8 : 5.573 : 120 : 22 : 442.9 : 4.606 : 121.3 : 19.5 : 64.8 : 12.132 Composition mol % wt % mol % wt % mol % wt % mol % wt % mol % wt % mol % wt % Hydrogen C4: n-butane i-butane C5: n-pentane i – pentane 2,2 DMProp cyclopentane C6: n-hexane 2 MP 3 MP 2,2 DMB 2,3 DMB cyclohexane cMP C7: n-heptane 2 MH 2,2 DMP cEP cMH Benzene Toluene 0 4.834 0.313 40.51 24.38 0.027 3.230 5.913 11.04 5.069 0.60 1.514 0.038 0.663 0.39 0.253 0.357 0.449 0.040 0.715 0.007 0 3.741 0.242 38.88 23.40 0.026 3.099 6.777 12.66 5.810 0.683 1.736 0.043 0.743 0.052 0.337 0.476 0.587 0.052 0.743 0.009 23.24 18.51 6.486 2.537 30.52 14.65 0 0.123 0.787 0.215 2.505 0.428 0 0 0 0 0 0 0 0 0 0.887 20.34 7.124 3.459 41.61 19.98 0 0.200 1.282 0.350 4.080 0.697 0 0 0 0 0 0 0 0 0 1.062 17.30 5.163 4.305 45.80 16.66 0 0.375 2.063 0.596 5.598 1.090 0 0 0 0 0 0 0 0 0 0.031 14.43 4.310 4.461 47.46 17.26 0 0.464 2.554 0.738 6.929 1.350 0 0 0 0 0 0 0 0 0 0 0.472 0.610 3.949 47.53 0.053 6.297 0.576 21.53 9.882 1.161 2.952 0.075 1.293 0.076 0.493 0.696 0.876 0.077 1.393 0.014 0 0.352 0.455 3.657 44.01 0.049 5.831 0.637 23.81 10.93 1.284 3.265 0.081 1.397 0.098 0.634 0.895 1.103 0.098 1.397 0.017 0 1.108 6.614 0.276 58.67 21.34 0 0.024 2.643 0.764 7.171 1.397 0 0 0 0 0 0 0 0 0 0 0.885 5.284 0.273 58.19 21.16 0 0.028 3.131 0.905 8.494 1.655 0 0 0 0 0 0 0 0 0 13.80 18.16 6.001 3.264 36.86 15.56 0 0.225 1.304 0.369 3.763 0.696 0 0 0 0 0 0 0 0 0 0.465 17.60 5.816 3.926 44.34 18.72 0 0.323 1.874 0.531 5.407 1.001 0 0 0 0 0 0 0 0 0
APPENDIX V
FLASH VESSEL – SPECIFICATION SHEET
EQUIPMENT NUMBER : V101 In Series : 1
NAME : Flash vessel In Parallel : none General Data
Service : - Buffer / Storage / Separation / Reaction
Type : - Packed Bed - Flash Separator
Position : - Horizontal - Vertical
Internals : - Demister / Plate / Coil / - none
Heating/Cooling medium : - none / Open / Closed / External Hxgr /________ - Type : n.a.
- Quantity [kg/s] : n.a. - Press./Temp.’s [bara/oC] : n.a. Vessel Diameter (ID) [m] : 2.00
Vessel Height [m] : 4.60 Vessel Tot. Volume [m3] : 14.45
Vessel Material : CS (1)
Process Conditions
Stream Data Feed Top Bottom
Temperature [oC] Pressure [bara] Density [kg/m3] Mass Flow [kg/s] : 120.0 : 19.5 : 64.87 : 12.127 : 120.0 : 19.5 : 39.28 : 6.481 : 120.0 : 19.5 : 424.87 : 5.646
Composition Mol % Wt % Mol % Wt % Mol % Wt %
Hydrogen C4: n-butane i-butane C5: n-pentane i – pentane 2,2 DMProp cyclopentane C6: n-hexane 2 MP 3 MP 2,2 DMB 2,3 DMB cyclohexane cMP C7: n-heptane 2 MH 2,2 DMP cEP cMH Benzene Toluene 13.798 18.164 6.000 3.265 36.858 15.555 0 0.225 1.305 0.369 3.763 0.697 0 0 0 0 0 0 0 0 0 0.464 17.602 5.815 3.928 44.341 18.713 0 0.323 1.875 0.531 5.407 1.001 0 0 0 0 0 0 0 0 0 22.328 18.740 6.561 2.568 30.874 14.821 0 0.125 0.797 0.218 2.535 0.433 0 0 0 0 0 0 0 0 0 0.841 20.354 7.126 3.462 41.623 19.981 0 0.201 1.283 0.351 4.082 0.697 0 0 0 0 0 0 0 0 0 1.061 17.303 5.162 4.306 45.793 16.652 0 0.375 2.063 0.596 5.597 1.090 0 0 0 0 0 0 0 0 0 0.031 14.446 4.310 4.463 47.459 17.258 0 0.464 2.554 0.738 6.929 1.350 0 0 0 0 0 0 0 0 0 Remarks: (1) CS = Carbon Steel
Designers : J.A.M Arnaud E.E. McLeary M. Tanfour K. T. Wudie
Project ID-Number : CPD3267
