Advanced process for Cost and Energy Saving

ACES21®

UREAPROCESSby TOYO

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TOYO: Leader in Urea ProcessTechnologySince its establishment in 1961, Toyo Engineering Corporation (TOYO) has been a leader inthe urea industry. TOYO has designed, engineered, constructed and commissioned over100 urea plants based on the TOYO Urea Process including its urea synthesis technologiesand urea granulation technologies.Using its own expertise, advanced technology and new thinking, TOYO has established theACES21® Process, which achieves energy saving and plant cost reduction withoutsacrificing high performance and high efficiency of the urea plant.

ACES21® has been developed together with P.T. Pupuk Sriwidjaja (PUSRI) of Indonesia as aCost and Energy Saving version of the ACES(*) Process.ACES21® is advanced technology to realize low investment cost and low energyconsumption for urea production. A major feature of this technology is that it reduces thenumber of components in the urea synthesis loop to simplify the system. This lessensconstruction costs with the installation of the reactor on the ground in the CO2 strippingprocess (resultantly existing urea reactor can be re-utilized for conventional solutionrecycle process or ammonia stripping process). In addition, the operation conditions of thesynthesis section have been optimized under lower operation pressure than in the previousprocess. As a result, a remarkable reduction in energy consumption has been achieved.

(*) ACES: Advanced process for Cost and Energy Saving urea production

CO2

UREA PRODUCT

NH3

RECYCLE CARBAMATE SOLUTIONHPSTEAM

LPSTEAM

LPSTEAM

LPSTEAM

UREA, EXCESS NH3CARBAMATE, H2O

UREAH2O

UREA

RECOVERED NH3, & CO2 VAPOR

LP STEAMGENERATION

COOLINGWATER

SYNTHESIS

RECOVERY

PROCESS CONDENSATETREATMENT

PURIFICATION

CONCENTRATION

GRANULATIONOR

PRILLING

NH3, CO2 & H2O

H2O & SMALL QUANTITIESOF NH3, & UREA

H2O

CLEAN PROCESS CONDENSATE

2NH3 + CO2 = NH4CO2NH2 – 38,000 cal/molNH4CO2NH2 = NH2CONH2 + H2O + 5,000 cal/molHence,2NH3 + CO2 = NH2CONH2 + H2O – 33,000 cal/mol

Sichuan Chemical Works (Group) Ltd. (China)

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Process Description

REACTOR

HPCARBAMATE

EJECTOR

NH3

PREHEATER

LS

TO LPD

MS

CO2

SC

STM

LS

LS

NH3 PUMP CO2 COMPRESSORCARBAMATE PUMP

MPABSORBER

LPABSORBER

PROCESS COND.STRIPPER

LS

HYDROLYZER

UREASOLUTION

TOPRILLING TOWER

ORGRANULATOR

SURFACECONDENSERS LS

C.W.C.W. C.W.

STRIPPERCARBAMATECONDENSER

MPDECOMPOSER

LPDECOMPOSER

VACUUMCONCENTRATOR EVAPORATOR

CO2NH3

TO MP ABSORPTION

TO MPDECOMPOSITION

BFW LPSTEAM

FROM NH3 PUMP

FROM CO2 COMP

FROM CARB. PUMP

MP STEAM

COND

REACTORSTRIPPER

EJECTOR

CONDENSER(VSCC)

SynthesisACES21® process synthesis sectionconsists of a reactor, a stripper and acarbamate condenser. Liquidammonia is fed to the reactor via theHP Carbamate Ejector which providesthe driving force for circulation in thesynthesis loop instead of the gravitysystem of the original ACES. Thereactor is operated at an N/C ratio of3.7, 182 °C and 152 bar. The CO2

conversion to urea is as high as 63% atthe exit of the reactor. Urea synthesis

solution leaving the reactor is fed tothe stripper where unconvertedcarbamate is thermally decomposedand excess ammonia and CO2 areefficiently separated by CO2 stripping.The stripped off gas from the stripperis fed to the Vertical SubmergedCarbamate Condenser (VSCC),operated at an N/C ratio of 3.0,180°C and 152 bar. Ammonia andCO2 gas condense to formammonium carbamate andsubsequently urea is formed by

dehydration of the carbamate in theshell side. Reaction heat of carbamateformation is recovered to generate 5bar steam in the tube side. A packedbed is provided at the top of theVSCC to absorb uncondensedammonia and CO2 gas into a recyclecarbamate solution from the MPabsorption stage. Inert gas from thetop of the packed bed is sent to theMP absorption stage.

Process Description

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Process Features

Ground Level ReactorThe sophisticated two-stage synthesisconcept employing a VSCC and anHP ejector enables the HP equipmentin the synthesis section to be laid-outvery compactly in low elevation. Thehighest level (the VSCC top) is about30 to 35 m(*), which is significantlylower than even the traditionalsolution recycle process in which thereactor is installed on the ground.(*) Depending on the plant’s capacity and

configuration

Vertical SubmergedCarbamate CondenserThe Vertical Submerged CarbamateCondenser (VSCC) functions tocondense NH3 and CO2 gas from thestripper to form ammoniumcarbamate and synthesize urea bydehydration of ammonium carbamatein the shell side, and to remove thereaction heat of ammonium carbamateformation by generating 5 bar steamin boiler tubes. The advantages of the verticalsubmerged configuration of thecarbamate condenser are summarizedas follows:

- High gas velocity, appropriate gashold up and sufficient liquid depthin the bubble column promote massand heater transfer.

- An appropriate number of baffleplates distribute gas bubbles in thecolumn effectively without pressureloss.

- A vertical design allows a smallerplot area.

Optimum Selection ofSynthesis ConditionIn the ACES21® Process, the VSCC isoperated at an N/C ratio of 3.0 whichallows relatively high temperature

GAS OUT

LIQ. IN

BFW + STEAM OUT

GAS IN

BFW IN

LIQ. OUT

U-tube Bundle

Baffle Plates

Packed Bed

Down Pipes

Process Features

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operation of the VSCC, renderingefficient heat transfer between theshell and the tube and higher reactionrate of ammonium carbamatedehydration to form urea. The reactor N/C ratio is selected ataround 3.7 to maximize CO2

conversion with appropriate excesspressure. Resultantly, a high CO2

conversion of 63% is achieved in thereactor at relatively low temperatureand pressure, i.e. 182 °C and 152 bar.

Less CorrosionTOYO and Sumitomo Metal Ind.,Ltd. (SMI) have jointly developed

new duplex stainless steel DP28W™for urea plant. The biggest advantage of duplexstainless steel is the excellent corrosionresistance and passivation property inurea-carbamate solution, whichenhances reliability of equipment andenables a reduction of the passivationair. In addition, DP28W™ has highmechanical strength which drasticallyreduces the thickness of the highpressure section components. DP28W™ is the optimal material forurea plants benefiting from the vastflow of feedback stemming from theextensive amassed experience of

TOYO and SMI.

Clean EffluentsThe liquid effluents from the ureaplant contaminated with NH3, CO2

and urea are processed in the processcondensate stripper-urea hydrolyzersystem.The process condensate leaving thesystem is purified to 1 ppm of ureaand 1 ppm of NH3. The exhaust air from the prillingtower (or granulator) is scrubbedthrough a packed bed scrubber toreduce the urea dust content to 30mg/Nm3-air.

EQ

UIL

IBR

IUM

CO

NV

ER

SIO

N (%

)

EQ

UIL

IBR

IUM

PR

ES

SU

RE

(Bar

)

80

70

60

50

40

200

180

160

140

120

100

EQUILIBRIUMPRESSURE

EQUILIBRIUMCONVERSION

EXCESS PRESSURE

OPERATING PRESSURE

CONDENSERN/C

REACTORN/C

2 2.5 3 3.5 4N/C

Grade Tensile Strength 0.2% Proof Stress Elongation Hardness(MPa) (MPa) (%) (Hv)

DP28W™ 934 647 42 281

DP12 822 610 42 251

25-22-2(S31050) 676 352 50 173

316L 518 234 52 144

Mechanical properties of DP28W™

Process Variation

TOYO owns or has the right tolicense various basic technologies tobe integrated with the urea plants inaddition to the new urea plantconstruction as a package.

Urea Finishing TechnologiesHigh Purified Industrial Grade UreaProduct: Urea crystal, Urea Prills,Urea Granules by Crystal SeparationProcessFertilizer Grade Urea Product: UreaSolution, Urea Prills, Urea

Granules by Vacuum EvaporationProcess

Product FormingTechnologiesUrea Prilling Process- Acoustic Vibrating Prill Head- Spinning Bucket (Tuttle Prilling

System)Urea Granulation Process- Spout-Fluid Bed Granulator

Pollution ControlTechnologiesProcess Condensate TreatmentSystem- Urea Hydrolyser- Process Condensate StripperUrea Dust Scrubbing System- Packed Bed Type Wet Scrubber

Supporting TechnologiesAnti-caking Treatment of Urea PrillsMelamine Off-gas Recovery SystemIntegration of Urea-Melamine Plants

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ATM.

DUSTSCRUBBER

GRANULATOR

SCREEN

CRUSHER

PRODUCT COOLER

PRODUCT

FEED UREASOLUTION

RECOVEREDUREASOLUTION

AIR

AIR

Urea prills 1-3mm Urea Granules 2-4mm Urea Granules 5-8mm Urea Granules

SKW Piesteritz GmbH(Germany)

P. T. Pupuk Iskandar Muda (Indonesia)

Process Variation

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Granting of Licenses andProject Execution As a licensor of urea processes andrelated technologies, TOYO offersvarious types of contracts from adirect license to the client to anindirect license through engineeringfirms. As the contractor, TOYOsupplies the complete urea plant tothe client on a turnkey lump-sumbasis. Therefore TOYO can control alltechnologies to be used for thedesign, engineering, construction andoperation of the urea plant withoutsublicensing agreements. This ensuressmoother and simple projectexecution under single contractualresponsibility of the contractor.

Training of Client’s OperatorsTOYO’s training program usuallyincludes training at TOYO’sEngineering Center using aproprietary Operation TrainingSimulator and Operation GuidanceSystem by which the trainees becomefamiliar with all phases of plantoperation including initial start-up andemergency shut-down prior to the in-plant training.

Provision of Plant LifecycleSolutionsTOYO provides solutions to meetclient needs for urea plants such as

operation and maintenance (O&M)services that sustain and enhance theproductivity of the client’s plant. Afterthe plant is accepted by the client,TOYO’s consulting services areavailable for:- Improvement of plant efficiency- Operation optimization- Trouble shooting- Pollution control- Product quality improvement- Plant maintenance- Plant retrofittingOne of TOYO’s solutions for themaintenance aspect is a Risk BasedInspection and Risk BasedMaintenance(RBI/RBM) systemand consulting servicefor fertilizer complexesprovided by TOYOtogether with ESRTechnology Ltd. (UK).The system is expectedto enable plant ownersto optimize their assetsthrough riskmanagement.

Remote Plant MonitoringSystemTOYO offers a Remote PlantMonitoring System (RPMS) service,which connects an actual operatingplant and a remote engineering officeusing DCS, a computer and theInternet to monitor plant conditionsin remote offices and provides afeedback of suggestions orrecommendations to the plant ownerafter the evaluation of monitored datautilizing TOYO’s professional know-how in the operation and maintenanceof urea plants.

ERP

Total Solutions by TOYO

MES

Control

Advanced Control Training/Education

PurchasingManagement

CorporateManagementLevel

PlantSupervisionLevel

FieldAutomationLevel

CostManagement

HumanResources

InventoryManagement

SalesManagement

PlantMaintenance

ProductionManagement Financials

Optimizer

APC

ESD

Sub-System

PLCReal TimeDatabaseDCS

FieldInstrument

UPOTS

Reporting

EquipmentMonitoring

Lot Tracking

Trend RPMS

Scheduling

OAS

TOYO’s Activities and Services

Head Office2-8-1 Akanehama, Narashino-shi,Chiba 275-0024, JapanTel: 81-47-451-1111 Fax: 81-47-454-1800URL: http://www.toyo-eng.co.jp/Tokyo Head Office11F Shin-Marunouchi Building 1-5-1 Marunouchi, Chiyoda-ku,Tokyo 100-6511, JapanTel: 81-3-6268-6611 Fax: 81-3-3214-6011Technology Research Center2-6-3 Akanehama, Narashino-shi, Chiba 275-0024, JapanTel: 81-47-408-2371 Fax: 81-47-408-2372

Overseas OfficesBeijingE. 7th Fl. Bldg. D, Fuhua Mansion, Chaoyangmen North Avenue No. 8, Beijing 100027, ChinaTel: 86-10-6554-4515 Fax: 86-10-6554-3212Shanghai17F, Shanghai Zhongrong Plaza, No.1088 Pudong South Road, Pudong New District, Shanghai 200122, ChinaTel: 86-21-5888-9935 Fax: 86-21-5888-8864/8874JakartaMidplaza 8th Fl., Jl. Jendral Sudirman Kav. 10-11, Jakarta 10220, IndonesiaTel: 62-21-570-6217/5154 Fax: 62-21-570-6215DohaBldg. No.9, Al Abbas Street(802), PO box 24131, Doha, QatarTel: 974-437-8860 Fax: 974-437-8861TehranWest Side / Ground Floor, No. 4 Alvand Street, Argentine Square, Tehran, IranTel: 98-21-8866-3088/4598 Fax: 98-21-8879-4019MoscowRoom No. 605, World Trade Center, Krasnopresnenskaya Nab., 12, Moscow 123610, RussiaTel: 7-495-258-2064/1504 Fax: 7-495-258-2065

Overseas Subsidiaries and Affiliated CompaniesSeoul, Shanghai, Bangkok, Kuala Lumpur, Mumbai, Luxembourg, Calgary, Houston, Brazil

Process PerformanceProduct Quality (Typical)

Nitrogen (N) Content 46.4 wt%Biuret Content 0.8 wt%Water 0.2 wt%

Consumption Figure (Typical, Granulation Case)Raw Material

NH3 (100%) 0.563 tonCO2 (100%) 0.731 ton

Note: (1) The loss from Ammonia Pump and CO2 Compressor is included.(2) Unit is per metric ton of granular urea.

Utilities (per metric ton of granular urea product)

UnitAll Motor Driven Case Steam Turbine Driven Case

Steam Export Steam Self Balance 42 bar 110 barSteam Import

22 bar, 300℃ ton 0.67 0.58

42 bar, 380℃ ton 0.80

110 bar, 510℃ ton 0.69

Steam Export

5 bar, Saturated ton 0.24 - - -

Cooling Water (Δt=10℃) m3 52 52 81 75

Electricity

Process kWh 105 105 21 21

Granulation kWh 24 24 24 24

Note: (1) All figures above include:- CO2 Compression - Ammonia and Carbamate Pumping- Urea Synthesis- Purification and Recovery- Urea Concentration- Urea Granulation- Process Condensate Treatment

(2) The figures above exclude:- air conditioning, ventilation, air heater,

steam trace, etc.- urea storage and bagging facility

(3) Ammonia Pump and Carbamate Pump are drivenby motor.

(4) Local conditions may change the figures above.(5) Unit is per metric ton of granular urea.

©2006 Toyo Engineering Corp.H19.11.20 SAN1

ACES21® is a registered trademark of Toyo Engineering Corporation in Japan (Registered Number 4309123).