PROCESS INTEGRATION FOR THE RETORTING OF OIL SHALE FINES Rick Sherritt, Gwen Chia, Ian Ng Procom Consultants Pty Ltd 30 th Oil Shale Symposium Golden CO 18-20 Oct 2010 1
PROCOM Consultants 2/5/11 OBJECTIVE • Show the capabilities of modern process simulator programs for design and optimization of an oil shale surface retorting process OUTLINE Ò Solid heat carrier (SHC) with complete combustion Ò Description of plant-wide model Ò Example of heat integration Ò Some observations Ò Conclusions 2
PROCOM Consultants 2/5/11 OIL EXTRACTION USING SOLID HEAT CARRIER (SHC) PROCESS Hot solids (usually shale ash) are recycled from the combustion step to mix • with the oil shale and heat it to pyrolysis temperature. The technology may include drying and preheating of feed streams as • well as heat recovery from shale ash and combustion gases. Pyrolysis vapours are cooled to separate product oil, water and gas. • 3
PROCOM Consultants 2/5/11 SHC WITH PARTIAL OR COMPLETE COMBUSTION OF SPENT SHALE Partial Combustion Ò SHC technologies such as ATP and Galoter use partial combustion of the spent shale to heat the recycled solids. Ò The air rate is regulated to burn only enough char to maintain the pyrolysis temperature. Complete Combustion • An alternative approach is to supply excess air/oxygen to ensure complete combustion of the spent shale. • Surplus heat must be removed to maintain the temperatures. 4
PROCOM Consultants 2/5/11 SHC USING DUAL CIRCULATING FLUIDISED BEDS (DCFB) Ò A circulating fluidized bed (CFB) combustor is well-suited for SHC with complete combustion. Excess heat is removed by generating É steam in membrane wall and external cooler. A wide particle size distribution (up to É 6mm) is accepted. CFB combustion proven at large-scale É in power generation industry. Achieves low NO x and SO 2 emissions É Ò A second CFB can be used for the pyrolysis reactor. Ò Loop seals fluidized by steam pass ash from combustor to pyrolyzer and spent shale from pyrolyzer to combustor. Reference: He et al. (1991). 5
PROCOM Consultants 2/5/11 STEPS FOR PROCESS INTEGRATION AND OPTIMIZATION Plant-wide process model 1. Heat and mass balances 1. Extract stream data 2. Heat loads, heat capacities, 1. supply and target temperatures Determine energy targets and pinch 3. temperatures Design heat exchanger network 4. Process change, design evolution 5. Design evaluations 6. Reference: Kemp, I. (2007) Pinch Analysis and Process Integration 2 nd Ed, Elsevier Ltd. UK. 6
PROCOM Consultants 2/5/11 PLANT-WIDE PROCESS MODEL Ò The plant is divided into 6 blocks using Aspen Plus hierarchy blocks Ò The current model does not include oil upgrading or sulphur and ammonia recovery Power Generation COOLING POWERGEN CW600 W POWER TO AREA 600 POWER HIERARCHY TRANSMISSION LINE Dry HIERARCHY Cooling NAPHT HA & KEROSENE NAPHTHA TO ST ORAGE TANK Gas DIESEL & LIGHT GAS OIL LTGASOIL Treatment TO ST ORAGE TANK FUELGAS GAS CW400 OFFGAS1 FLAREGAS OILRCVRY TO FLARE AREA 500 ST300 AREA 400 Oil HIERARCHY HIERARCHY Recovery SOURH2O1 VAPOUR HEAVYOIL Shale Water Processing Treatment FREE-H2O FEEDMIX SHALPROC FUELGAS1 AREA 300 KEROGEN OILSHALE WETWATR OIL SHALE MINERALS HIERARCHY RAWWATR SWSOFFG AREA 700 FROM CRUSHED GAS MAKE-UP ST OCKPILE HIERARCHY TO FLARE WATER SEC-AIR WATER1 FLD-AIR AMBIENT FLUE GAS AIR CON-AIR STACKGAS TO ST ACK WET ASH PRI-AIR WETASH 7 TO MINE
PROCOM Consultants 2/5/11 SHALE PROCESSING BLOCK Ò The shale processing block includes models for pyrolysis, combustion, heat recovery, gas cleaning and wetting of ash. 341 Gas 334 STACKGAS(OUT) OSHTR Cleaning 301 OILSHALE(IN) VAPOUR(OUT) Optiona l pre hea ting 303A 339 GASCLEAN 306 HIERARCHY Pyrolyser Recycled Waste Heat Ash PYROLYSR Boiler 304 315 HEAVYOIL(IN) HIERARCHY WHB 316 317 HIERARCHY Spent ST300 327 Shale 330 WATER2(IN) 307 CON-AIR(IN) COMBUSTR Combustor 337 321 HIERARCHY SEC-AIR(IN) Ash SAHTR 329 340 Cooler 308A ST303 03-K02 323 FBC ASHMX Ash HIERARCHY MIXE R ST302 Moistening 342 FUELGAS2(IN) FLD-AIR(IN) 331 PAHTR Heat to power ST304 WETASH(OUT) generation 328 PRI-AIR(IN) 308 Q QTOT ST300(OUT) 03-K01 MIX ER 8
PROCOM Consultants 2/5/11 PYROLYSER SUB-MODEL Ò The pyrolyser sub-model includes stoichiometric reactors for heavy oil coking, kerogen pyrolysis, mineral decomposition and vapour-phase cracking. Recycled ash from combustor Recycled 315 315(IN) Heavy Oil Pyrolysis Vapour to Oil Recovery 304 304(IN) Oil Shale 306(OUT) 303 303A(IN) 03-MIX1 Vapour phase 306 cracking 03-CRAK1 DUPMIX 305G 305 Mineral Vapour-phase 03-COKE cracking decomposition 305D 305F Heavy oil 03-PYR1 305A 03-PYR2 coking 305B 03-SEP1 Heavy oil coking Kerogen 305C Kerogen Mineral pyrolysis pyrolysis decomposition and particle 305E Dust attrition entrainment SIZE5 Ò Particle attrition and dust entrainment SCREEN Spent shale to are included. CFB combustor 307 307(OUT) 9
PROCOM Consultants 2/5/11 CFB COMBUSTOR SUB-MODEL Ò The CFB combustor sub-model includes dense bed, dilute phase freeboard, cyclone and external cooler. Ash to pyrolyser 315 315(OUT) Combustor cyclone RECCYCL 342(IN) 342 310 316 316(OUT) Fuel HIERARCHY Flue Gas to Gas 03-FREEB Heat Recovery 309A(IN) 309 Combustor dilute phase Secondary air from fan 308B 337 337(OUT) 307FINE FLDBDSPL Ash to Char combustion 311 Cooler Mineral oxidation 03-PSDSP Mineral decomposition 307(IN) 307 SCREEN Spent shale Sulphur capture 308A from pyrolyser Heat to Power Generation 03-FLDBD 307COARS RCOOLR 312 ST302 ST302(OUT) HEATER Primary Combustor Combustor air from fan dense phase external cooler and seal 308A(IN) 308 10
PROCOM Consultants 2/5/11 POWER GENERATION BLOCK Ò The power generation block includes a cascade of back-pressure power turbines. Ò Steam is expanded to sub-atmospheric pressure then condensed against dry cooler. Ò Boiler feed water is preheated with drawn off IP/LP steam Ò Self-contained and highly optimized W W1 TOTWRK W4A WOUT POWER(OUT) Power turbines MIXE R IP1 LP3 IP2 IP3 LP1 LP2 LP4 HP1 W3 IP4 W6 W7 614 S15 FROMSH3 M5 Condenser 613-2 613-3 613-4 614-2 614-3 614-4 FROMRH2 S8A 613A 613-2A 613-3A 614A 614-2A 614-3A CWPOWGEN 636 CW600(OUT) CONDENSE S1 TORH1 BOILERS W8 S2 S3 S4 S5 S6 S7 ST300 ST300(IN) V1 HIERARCHY 625 TORH2 W5 W4 623 Economiser M2 M1 M3 S22 M4 624 Evaporator TOECO 634Z 633Z 635Z 617 635 S620 FWH6 FWH5 633 634 632 FWH4 FWH3 FWH2 FWH1 Superheaters P2 620B 620A CWP 619 618C DEAERATE Reheaters 629 V5 S30 631 Feedwater Feedwater Deaerator S16 heaters heaters 11
PROCOM Consultants 2/5/11 MODEL COMPONENTS FOR GREEN RIVER OIL SHALE Stream Substream Substream MIXED CISOLID Aspen Pure Pseudo- User-Defined Databank Components components Components INORGANICS C 5 – 150 o C SO 2 H 2 CH 4 FeCO 3 NaAlSi 2 O 6 •H 2 O SiO 2 H 2 O Light Naphtha Siderite Analcite Quartz Free Water 150 o C – 205 o C NH 3 N 2 C 2 H 4 CaMg(CO 3 ) 2 NaAlSi 3 O 8 Kerogen KAl 2 (Si 3 Al)O 10 (OH) 2 Heavy Naphtha Dolomite Illite Albite 205 o C – 260 o C H 2 S O 2 C 2 H 6 CaCO 3 FeS 2 KAlSi 3 O 8 Char Kerosene Calcite Pyrite K-Feldspar NaAlSi 2 O 6 260 o C – 315 o C H 2 O Ar C 3 H 6 Fe 3 O 4 Fe 0.875 S Dehydrated Light Gas Oil Magnetite Pyrrhotite Analcite MgO NaAlO 2 315 o C – 425 o C CO 2 C 3 H 8 FeS Magnesium Sodium Heavy Gas Oil Troilite Oxide Aluminate CaO 425 o C – 600 o C CO C 4 H 8 Fe 2 O 3 Al 2 O 3 Calcium Vacuum Gas Oil Hematite Corundum Oxide Solids sub-stream is divided into 13 particle size 600 o C+ C 4 H 10 Residuum intervals 12
PROCOM Consultants 2/5/11 PROPERTIES OF USER-DEFINED COMPONENTS Kerogen n Cha har FreeH2O Fr CH 1.5 N 0.025 O 0.05 S 0.005 CH 0.42 N 0.056 O 0.02 S 0.008 H 2 O Formula Molecular weight, kg/kmol 14.833 13.795 18.015 39549 34042 - Gross heat of combustion kJ/kg -1489.7 1115.9 -15000 Standard heat of formation kJ/kg -22097 15394 -285929 Standard heat of formation kJ/kmol [ ] 2 3 4 [ ] C p kJ/kmol K c c T c T c T c T where T T K T Heat capacity ⋅ = + + + + ≤ ≤ 1 2 3 4 5 min max c 1 3.311·10 0 -1.626·10 0 5.084·10 1 c 2 7.793·10 -2 5.943·10 -2 2.131·10 -1 c 3 -2.453·10 -5 -2.464·10 -5 -6.314·10 -4 c 4 0 0 6.487·10 -7 c 5 0 0 0 T min , K 273 273 273 T max , K 750 1000 623 13
PROCOM Consultants 2/5/11 PYROLYSER STOICHIOMETRY (1) Pyrolyser reactors include reactions for oil shale drying and mineral decomposition Reactant nt Reaction E n Equation n Extent nt Free water FreeH 2 O à H 2 O 1.0 NaAlSi 2 O 6 · H 2 O à NaAlSi 2 O 6 + H 2 O Analcite 1.0 NaAlCO 3 (OH) 2 à NaAlO 2 + CO 2 + H 2 O Dawsonite 0.5 0.875FeS 2 + 0.75H 2 à Fe 0.875 S + 0.75H 2 S Pyrite 0.46 3FeCO 3 à Fe 3 O 4 + CO + 2CO 2 Siderite 0.3 14
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