Post on 22-Mar-2018
Novel Approach to Ammonia Plant Revamps with ZoneFlow™ Reactor Technology
SANJIV RATAN & Michael Ralston
ZoneFlow Reactor Technologies, LLC (ZFRT), USA Prof. Juray de Wilde,
Universite Catholique De Louvain (UCL), Belgium
ZoneFlowTM Reactor Technologies, LLC
Presentation Outline
Introduction Steam Reforming “pellet” catalyst - Status quo ZoneFlowTM (ZF) Reactor Technology - an innovative
breakthrough ZF development status and validation programs Application of ZF Reactor Technology in ammonia plants
• ZF Single-Pass Reactors (ZF-SP)• ZF Convective Pre-Reforming Reactors (ZF-CPR)• ZF for Post Reforming (ZF-PR)
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Introduction
Projected global growth for nitrogen fertilizers: 2% per year
Ammonia plant revamp / expansion is the potential driver
Expansion often constrained by primary reformer / SMR (dP, TSM, firing)
Proven solutions in place for typical 20-30% additional capacity but often constrained by existing SMR (mainly catalyst ) limitations
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Ammonia Plant Syngas Generation Front-end
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Steam Reforming Pellet Catalyst - Status Quo
Inherent deficiencies of the conventional "pellet" steam reforming catalyst, limiting reformer capacity increase: • high pressure drop• catalyst attrition / breakage from thermal cycling• limited heat transfer and associated higher tube
temperatures• flow / temperature non-uniformity due to random packing• very low catalyst effectiveness
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ZoneFlow Reactor Technology– an Innovative Breakthrough
Advanced high-performance structured catalyst Step improvement of key performance
parameters • up to 2 times higher heat transfer (along with internal radiative transfer)• up to 70% lower pressure drop• up to 10 times higher catalyst effectiveness• high strength metal substrate; longer stable life• annular flexible casing; near-wall flow jets• adaptive structure for Convective pre-reforming
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from random packing to engineered foil structure; also non-acidic and steam stable
from strength-limited voidage of ~ 50 % to ~ 90% voidage with robust substrate
from limited surface (GSA) enhancement to high GSA fin structure
Conventional SMR Catalyst v/s ZF Reactors
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ZF offers step reduction in dP combined with multifold increase in heat transfer
ZoneFlowTM
structuredCatalyst
Conventional pellet
catalyst
Conventional SMR Catalyst v/s ZF Reactors
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ZoneFlowTM
structuredCatalyst
Conventional pellet
catalyst Increased catalyst effectiveness ; higher
resistance to coking and upsets ; longer life
from random packing tube wall contact to flexible casing for uniform proximity to wall
from limited crush strength against thermal cycling to durable metal substrate
from diffusion-limited active site access to micro-layered full surface access
No attrition from thermal cycling; stable dPand flow uniformity over full operating life
ZF CFD Modeling (dP and Heat Transfer)
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0%
50%
100%
150%
200%
250%
0% 50% 100% 150% 200%
Relative ΔP
New SMRs
Revamps
1.E-03
1.E-02
1.E-01
1.E+00
1.E+01
1.E+02
5.E+01 5.E+02 5.E+03 5.E+04 5.E+05 5.E+06
hf /
dP/
dz
dP/dz
Empty tube
Different ZF Casing Designs
Relat
ive H
eat T
rans
fer
Coef
ficien
t
ZF Kinetic Modeling and FEA Analysis
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ZF Commercial Demonstration
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Installation Operation
Extraction
Demonstrated Results Compared to Pellet Tubes
80o C lower TMT 24% lower pressure drop No hot spots ZF operation >15,000 hrs with several thermal cycles
Lower S/C ratio operation was not available
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ZFRT Pilot Plant
At Materials and Process Engineering (IMAP) Division in Université catholique de Louvain (UCL), Belgium
Facilities and campaigns for extensive testing of ZF reactorsunder various commercial conditions and beyond
In collaboration with Professor Gilbert Froment Operational 2Q 2018
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ZFRT Pilot Plant Installation
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Ammonia Plant Revamps
Revamp approaches• ZF-SP reactors replacing pellets to allow capacity increase
without added dP or increase in tube temperatures
• Adding ZF-CPR Reactors in primary reformer convection zone to utilize high grade convective heat for producing additional hydrogen instead of steam
• Use of ZF-PR reactors in post-reformers or heat-exchange reformers for step capacity increase , which are inherently heat-transfer limited and capital intensive
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Typical Reforming Section of a Ammonia plant
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500-550 oC
780-820 oC
10-13% CH40.3-0.5% CH4
450-500 oC
950-1000 oC H2/N2 vol. ratio ~3
ZF-SP Reactors for Stressed SMRs
Stressed SMR Indicators / Attributes • Pressure drop (and build up) limiting throughput• Loss of catalyst activity and related heat transfer or
Shorter EOR activity• Hotter tubes / Hot spots • Carbon formation at inlet • Catalyst bridging / settling from thermal cycling• Shorter (remaining) tube life
Replacing (pellet) catalyst in these SMRs with ZF-SP Reactors can overcome these deficiencies
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ZF-SP for De-Stressing of SMR
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SMR De-Stressing SMR Design
Stressed Operation
ZF-SP replacing pellets
Relative Capacity, % 100 95 100Capacity limitations - dP, TSM removedS/C Ratio 3.3 3.5 3.2Outlet temp, C 800 793 804Approach to Equilibrium EOR C -10 -12 -7CH4 slip, vol % 12 12 12Radiant Pressure drop, bar 2.8 2.8 2.3Relative Radiant duty % 100 97 99Avg. Heat flux kW/m2 75 72 75Bridgwall temp, C 950 950 948Max. Tube Skin temperature C 860 860 857
ZF-SP Reactors for Debottlenecking
Achieve capacity in excess of nameplate (~ 105 %), while utilizing design margins in SMR burners and fans
Higher average heat flux without exceeding tube design temperature
Improved temperature uniformity Extended tube life and improved reliability and availability Better catalyst performance and “life cycle” costs Extended EOR Optimized operation and reforming severity
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ZF-SP for Debottlenecking Reference ZF-Radiant
Relative Capacity, % 100 105Capacity limitations dP, TSM removedS/C Ratio 3.3 3.1Outlet temp, C 800 810Approach to Equilibrium C -10 -7CH4 slip, vol % 12 12Radiant Pressure drop, bar 2.8 2.5Relative Radiant duty % 100 103Avg. Heat flux kW/m2 75 77Bridgwall temp, C 950 950Max. Tube Skin temperature C 860 860
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Pre-reforming
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In-situ efficient use of higher grade convective heat using existing process coils
Syngas
SteamMethane
Mixed feed
Convective zoneFlue gas to stack
Radia
nt Zo
ne
AdiabaticPre-
reformer
Adiabatic pre-reforming
(APR)
ZoneFlowTM
ZF Convective Pre-reforming (ZF-CPR)
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Non-adiabatic convective pre-reforming using ZF-CPR inserts In-situ horizontal loading in the mixed feed superheat coils Avoids major modifications around the primary reformer and
also the related extended downtime Tailored structured packing for very low dP, high GSA and (low
temp reforming) activity Further optimization of dP in combination with ZF-SP in SMR
radiant tubes For revamps, up to 15% additional reforming without increasing
SMR firing duty.
ZF-CPR based Revamping
Existing ZF + CPRRelative Capacity, % 100 115S/C Ratio 3.4 2.8SMR inlet temp, C 550 550 / 575 1)SMR outlet temp, C 804 804 / 821 2)Approach to Equilibrium C -10 -7CH4 slip, vol % 12 13.2 / 12Radiant Pressure drop, bar 2.5 2.3Avg heat flux kW/m2 75 75-77Relative Radiant duty 100 100 / 103Bridgewall temp, C 950 < 960TSM C 860 845/ 865 1) 2)
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* Exploiting of existing plant design margins, tube skin and bridgewall temps increase are minimum with lower ATE and enhanced heat transfer
Post Reforming integration with Secondary reformer
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Courtesy KBR
Expansion Revamp Using Post-Reforming
Post-reforming is a proven solution for 25-30% additional H2 without increasing SMR radiant duty.
Proportionate N2 from process air circuit revamping Post-reformer is a heat transfer-limited convective heat
exchange reformer ZF-PR can significantly lower the size and cost of post-
reformer because of its heat transfer and dP advantages When combined with CPR, can provide upto 40%
additional equivalent H2
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ZF Post-Reforming + CPR based Revamp
Existing ZF-PR + CPRRelative Capacity, % 100 135S/C Ratio SMR / PR 3.4 3.0Inlet temp SMR / PR C 550 550 / 575 Outlet temp, SMR / PR tube C 804 804-820* / 915CH4 slip SMR / PR vol % 12 12 / 3.5Seco Reformer outlet temp, C 980 1020H2/N2 ratio in MUG 3.0 2.9 -3.1Total inerts in MUG vol % 1.5 ~ 2.5Relative SMR radiant duty 100 100
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* Exploiting of existing plant design margins, tube skin and bridgewall temps increase are minimum; with lower ATE and enhanced heat transfer
Conclusions
SMR performance governed mainly by its catalyst Current pellet-catalysts carry inherent deficiencies, especially
for uprating ZoneFlowTM Reactor Technologies (ZFRT) innovative structured
catalyst offers exceptional solutions for cost-effective reformer capacity increase for ammonia plant revamps, with OPEX and CAPEX benefits.
Successful demonstrations and pilot plant for testing under commercial / client-specific conditions
ZoneFlowTM reactors carry unmatched merits and benefits for cost-effective revamping of ammonia plant front ends .
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ZoneFlow Reactor Technologies, LLC
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For additional information, contact:Sanjiv RatanDirector of Marketing and Prod Devsratan@zoneflowtech.com+1-951-538-5501
Thank You !