Download - AIChE 2011 Cogen Screening 05
-
8/2/2019 AIChE 2011 Cogen Screening 05
1/21
Cogen Screening for Improved Performanceand CO2 Reduction: Revisiting the R-Curves
2009 Shell Global Solutions (US) Inc. All rights reserved.
By Oscar Aguilar
March 2011
2/39Cogen Screening & Targeting for Improved Performance
Disclaimer
The companies in which Royal Dutch Shell plc directly or indirectly owns investments are separate entities. In this
publication the expressions "Shell", "Group" and "Shell Group" are sometimes used for convenience where references are
made to Group companies in general. Likewise the words "we", "us" and "our" are also used to refer to Group companies in
general or those who work for them. The expressions are also used where there is no purpose in identifying specific
companies.
Shell Global Solutions is a network of independent technology companies in the Shell Group. In this publication the
expression Shell Global Solutions is sometimes used for convenience where reference is made to these companies in
general, or where no useful purpose is served by identifying a particular company.
The information contained in this publication contains forward-looking statements, that are subject to risk factors which
may affect the outcome of the matters covered. None of Shell Global Solutions, any other Shell company and their
respective officers, employees and agents represents the accuracy or completeness of the information set forth in this
publication and none of the foregoing shall be liable for any loss, cost, expense or damage (whether arising from negligence
or otherwise) relating to the use of such information.
The information contained in this publication is intended to be general in nature and must not be relied on as specific
advice in connection with any decisions you may make. Shell Global Solutions is not liable for any action you may take as
a result of you relying on such material or for any loss or damage suffered by you as a result of you taking this action.
Furthermore, these materials do not in any way constitute an offer to provide specific services. Some services may not be
available in certain countries or political subdivisions thereof.
Copyright 2010 Shell Global Solutions (US) Inc.. All copyright and other (intellectual property) rights in all text, images
and other information contained in this publication are the property of Shell Global Solutions (US) Inc., or other Shellcompanies. Permission should be sought from Shell Global Solutions (US) Inc. before any part of this publication is
reproduced, stored or transmitted by any means, electronic or mechanical including by photocopy, recording or information
storage and retrieval system.
-
8/2/2019 AIChE 2011 Cogen Screening 05
2/21
3/39Cogen Screening & Targeting for Improved Performance
Presentation Outline
1. Introduction
4 Some Definitions
4 Cogen plant design/optimization
4 Challenges in Cogen design/retrofit
2. Cogen Screening & Targeting
4 Main features
4 Cogen configurations
4 Plant customization
4 Results comparison
3. Case Study
4 Cogen targeting for an existing site
4. Conclusions and Future Work
4/39Cogen Screening & Targeting for Improved Performance
1. I N T R O D U C T I O N
-
8/2/2019 AIChE 2011 Cogen Screening 05
3/21
5/39Cogen Screening & Targeting for Improved Performance
i Production of power and useful heat from a common energy source
4 Energy cascades to produce power and then meets a heating demand
i Cogeneration is an operating mode for individual units in a CHP system
4 Some steam may be directly delivered by a boiler while some is expanded in aturbine
Introduction
i A system that satisfies the heat and power demands from other processes
4 A combined cycle plant (CCP) produces heat, but only delivers power
4 Heat and power are utilities directly consumed by users (CHP = Utility Systems)
Combined Heat and Power (CHP) Plant
Cogeneration
6/39Cogen Screening & Targeting for Improved Performance
Introduction
Overview of a CHP Plant
i A series of interconnected units transforming feeds into products (utilities)
4 Flows with direct cost implications: Fuel, Power, Water, Emissions (mainly)
GTg
HRSG
Cool Sys
CTgEM
LD
Deaer
BTg
Fan
BO
Cond
Treatment
Plant
pumpMTgProcess
Steam
GridElectricity
ProcessElectricity
Several
Fuels
Condensate
Returns
Raw Water +
Treat Chems
Shaft
Power
Heat
Rejection
Atmospheric
Emissions
Blowdown +
Water Rejects
-
8/2/2019 AIChE 2011 Cogen Screening 05
4/21
7/39Cogen Screening & Targeting for Improved Performance
Introduction
CHP/Cogen Plant Optimization
i Objective: Determine the flowsheet conditions that Minimize Opex
4 Establish how to operate each piece of equipment
4 For an existing site, no changes in configuration considered
i Simulation / Optimization tools widely used for these applications4 Integrated approach is needed as all variables are interrelated
4 Streams across boundaries will establish cost implications
Many choices tosupply MP steam
LD
BO BOBO
MTgBTgBTg
GTg
HRSG Each option hascomplex plant-wide
implications!
Options for CHP Optimization:
8/39Cogen Screening & Targeting for Improved Performance
Introduction
CHP/Cogen Plant Design (grassroots)
i Objective: Determine the flowsheet configuration that will minimize TotalCost (Opex + Capex)
4 Equipment types, number of units, sizes, interconnections
4 Plus the operational variables for a given design
iComplex problem, just a few non-commercial tools have been developed4 In general, no specialized tools to address this type of problems
i Typically addressed by trial-error using (operational) simulation/optim tools!
4 Non-systematic, tedious and time-consuming
BO
GTg
HRSG BO
BO
BO
GTg
HRSG
GTg
HRSG
GTg
HRSG
GTg
HRSG
BO
BOBO
BO
BO
GTg
HRSG
GT
HRSGBO BO BO
GTg
HRSG
GTg
HRSG
What types ofequipment?
How manyunits?
How to connectthem?
How to sizethem?
+All the
operationalissues
Options for CHP Design:
-
8/2/2019 AIChE 2011 Cogen Screening 05
5/21
9/39Cogen Screening & Targeting for Improved Performance
Introduction
CHP/Cogen Plant Retrofit
i Objective: Determine changes in configuration that will minimize Opex +Capex (or just min Opex for a given Capex)
4 Also design + operational variables to be defined
i A special case of the design problem with some features fixed (existing)4 Reduced searching space compared to grassroots problems
i Again, typically involves a trial-error procedure using operational tools
Options for CHP Retrofit:
10/39Cogen Screening & Targeting for Improved Performance
Introduction
Challenges in CHP/Cogen Design/Retrofit
i Commercial software mainly intended for operational applications
4 For existing plants with a fixed configuration
i Users have to figure out several configurations to test
4 Mainly based on experience, speculation on the best design
iTrial-Error is time consuming and can miss better opportunities4 May not make consistent comparisons
i Other concerns:
4 What is the best a plant can achieve? (e.g. economics-efficiency-emissions)
4 E/E/E performance trends with configuration changes
4 How to size units to match a certain configuration?
4 Can other designs with similar E/E/E performance save capex
A systematic approach needed to tackle CHP design/retrofit cases
-
8/2/2019 AIChE 2011 Cogen Screening 05
6/21
11/39Cogen Screening & Targeting for Improved Performance
2. C O G E N S C R E E N I N G &T A R G E T I N G
12/39Cogen Screening & Targeting for Improved Performance
Cogen Screening & Targeting
Main features
i Quick screening of promising Cogen configurations
4 Side-by-side comparison basis to identify best performers
i Consider Economics-Efficiency-Emissions at the same time
4 Conventionally, only one aspect taken into account
iSystematic guide to define the design/retrofit of the plant4 Practically all major options are compared
4 Ensure decisions are taken in the right direction
4 Top performers can be further evaluated for capex savings
i Customization options to represent different systems
4 Practical problems encountered in industry
i Alternatives beyond existing configuration for retrofit cases
Screening for New Designs + Targeting for Retrofit Cases
-
8/2/2019 AIChE 2011 Cogen Screening 05
7/21
13/39Cogen Screening & Targeting for Improved Performance
Cogen Screening & Targeting
Data Input
i Net steam (heating) demands/surplus and headers pressures
4 Up to 4 steam headers, temperature defined from steam turbines
HEADERS' CONDITIONS STEAM DEMANDS/SURPLUS
VHP Press = 630.0 4 VHP Steam
Tsat = 494.0 2 2 0.00 4
Steam Flow = From Process
Aprox VHP Heat = 0.00 2
HP Press = 400.0 psig HP Steam
Tsat = 448.2 F 2 -145.00 klb/hr
Steam Flow = From Process
Aprox HP Heat = 179.86 MMBtu/hr
MP Press = 250.0 psig MP Steam
Tsat = 406.0 F 1 207.00 klb/hr
Steam Flow = To Process
Aprox MP Heat = 248.86 MMBtu/hr
LP Press = 50.0 psig LP Steam
Tsat = 297.7 F 1 231.00 klb/hr
Target LP Temp = 320.0 F Steam Flow = To ProcessAprox LP Heat = 255.00 MMBtu/hr
VP Press = 0.597 psia
Temp = 85.0 F Net Stm Dem = 683.73 MMBtu/hr
293.00 klb/hr
Deaerator Press Dea = 21.6 psig Process BFW = 622.20 klb/hr
Tsat Dea = 261.4 F Condens Rtn = 404.00 klb/hr
BFW Final BFW T = 262.0 F Proc Wtr Dem = 511.20 klb/hr
psig
klb/hr
MMBtu/hr
F Surplus
Surplus
Demands
Demands
14/39Cogen Screening & Targeting for Improved Performance
Cogen Screening & Targeting
Data Input
i Other site data such as available fuel, power demands, prices
4 Fuel data, CO2 charges, CO2 from external power supplier
FUEL DATA
Fuel Type = 2
Fuel LHV wt = 46.28 1
Fuel LHV wt = 46.50 MJ/kg
Fuel LHV vol = 33.56 1
Fuel LHV vol = 51.00 MJ/Nm3 25C
Fuel HHV/LHV = 1.107 ( - )
Fuel HHV/LHV = 1.10 ( - )
CO2 Release = 2.589 kg-CO2/kg-fuel
CO2 Release = 2.50 kg-CO2/kg-fuel
CO2 Release = 55.942 1 1
CO2 Release = 130.00 g-CO2/ MJ-f uel LH V
Natural Gas
MJ/kg
MJ/Nm3 25C
LHVg-CO2/MJ-fuel
ECONOMIC DATA
Pow Imp Price = 58.28 $/MWh
Pow Exp Price = 58.28 $/MWh
Fuel Price LHV = 6.86 $/MMBtu
Econ Imp Eff = 40.2%
Econ Exp Eff = 40.2%
Onsite CO2 Chrg= 30.00 $/ton
Extern CO2 Chrg= 0.00 $/ton
Mkup Wtr Cost = 1.00 $/ton-water
Desal Wtr Value = 0.26 $/ton-water
Cooling Cost = 1.71 $/MWh
SITE DATA
Pow Demands = 36.00 MWe
Cond Return T = 122.0 F
Mkup Wtr Temp = 77.00 F
Include DA Stm = 2
Heat Calcs Ref 4
Exter Pow CO2 = 0.575 ton/MWh
Equiv Eff = 35.0%
Op Hours = 8760.0 hrs/yr
Cond Return Temp
No
-
8/2/2019 AIChE 2011 Cogen Screening 05
8/21
15/39Cogen Screening & Targeting for Improved Performance
Cogen Screening & Targeting
Main Configuration Options
1. Boilers Only (pure steam system)4 Stand-alone boilers supply steam, all power imported
2. Simple steam turbine extraction
4 Some power extracted in ST before delivering steam
3. Enhanced ST extraction4 Additional VHP header to extract more power from ST
4. Enhanced ST extraction + Condensing4 Extra steam sent to condensing ST
5. Boiler + Gas Turbine with Supp-Fired HRSG4 Steam: Boiler + HRSG with duct firing (SF), Power: GT + bck-press ST
4 Steam producers sized to exactly match demands
6. Boiler + GT w SF HRSG + Condensing4 Steam: Boiler + SF-HRSG, Power: GT + BP ST + condensing ST
4 Extra steam sent to condensing ST
16/39Cogen Screening & Targeting for Improved Performance
Cogen Screening & Targeting
Main Configuration Options (cont)
7. GT w SF-HRSG + Condensing4 All steam from SF-HRSG, extra steam to CT (CT=GT)
8. GT w SF-HRSG4 GT sized to exactly match steam demands (SF=GT)
9. GT w Unfired HRSG4 Larger GT sized to exactly match steam demands (SF=0)
10. GT w UF-HRSG + Condensing4 Additional steam sent to a condensing ST ( CT= GT)
11. GT w UF-HRSG + Exhaust Bypass4 Larger GT as not all exhaust gases produce steam
12. GT w UF-HRSG + Bypass + Condensing4 Even larger as some extra steam to CT
-
8/2/2019 AIChE 2011 Cogen Screening 05
9/21
17/39Cogen Screening & Targeting for Improved Performance
Cogen Screening & Targeting
Customization Options
i Performance parameters can be edited to represent different systems
4 Several units of each type can be represented (e.g. bulk efficiency)
4 Duct firing, condensing steam, GT exhaust bypass can be adjusted
INDIVIDUAL PERFORMANCE PARAMETERS
Boiler Eff = 85%
ST Elec/Mech Eff = 90%
Extra Cond Duty = 40% % Stm heating
Sup Firing = 100% %Max
STg1 Isen Eff = 80%
STg2 Isen Eff = 80%
STg3 Isen Eff = 80%
STg4 Isen Eff = 87%
GT Gross Eff = 34%WHB Correction = 1.000
Desal Water = 0.00 ton/MWh
Pow for Cooling = 2.00 kWe/MW-cool
BFW pmp Eff = 69%
GT Fuel Compress Pow = 5.0% %GT Gross Pow
BD Fraction = 3.0% of steam
18/39Cogen Screening & Targeting for Improved Performance
3. C A S E S T U D Y C H P R E T R O F I T
-
8/2/2019 AIChE 2011 Cogen Screening 05
10/21
19/39Cogen Screening & Targeting for Improved Performance
Case Study
Existing CHP plant
i Main driver: Reduce CO2/Energy/Opex cost-effectively
4 What is the best the plant can achieve? How to get there?
ai
DA
HR2
LD3
LD2 32CWP
BO2
Conden
Cool Sys
HPLP
GTg
P
PCW
P4
P3
P2
HR2GTg
HR2GTg
STG 6RGC 11RGC 3WSP 1ovhdC 4AbsP
32CWP1ChgP 7RGC M P LP
20/39Cogen Screening & Targeting for Improved Performance
Case Study
Short-cut version of the system
i Performance parameters adjusted to represent the existing system
4 Letdown reflected as lower efficiency in ST power production
4 Drivers w/out electric motor option are part of steam demands
167.5 MMBtu/hr 0.0 / 1365.3 MMBtu/hr Temps OK!
125.0 klb/hr 136.0 MW
VHP 630.0 psig 499. 8 k lb/ hr 735. 9 F
494.0 F 0.0 MMBtu/hr
0.00 0.0 klb/hr 0.0 klb/hr
0.0 MW
HP 400.0 psig 638.6 F
448.2 F -179.9 MMBtu/hr
26.14 207.0 klb/hr 5.2 MW -145.0 klb/hr
4.4 MW
MP 250.0 psig 549.0 F
406.0 F 248.9 MMBtu/hr
52.75 417.8 klb/hr 0.0 MW 207.0 klb/hr
19.6 MW
LP 50.0 psig 320.3 F
Dea Steam 297.7 F 255.0 MMBtu/hr
184.5 klb/hr 147.3 klb/hr 231.0 klb/hr
10.1 MW
VP 0.597 psia
85.0 F 129.6 MMBtu/hr
BO
GTg
WHB
STg
STg
STg
STg
EQUIPMENT PERFORMANCE PARAMETER
Boiler Eff = 85%ST Elec/Mech Eff = 90%
Extra Cond Duty = 40% % Stm heating
Boiler Output = 20% %Tot steam flow
Sup Firing = 0% %Max
STg1 Isen Eff = 80%
STg2 Isen Eff = 80%
STg3 Isen Eff = 80%
STg4 Isen Eff = 87%
GT Gross Eff = 34%
WHB Correction = 1.000
Desal Water = 0.00 ton/MWh
Pow for Cooling = 2.00 kWe/MW-cool
BFW pmp Eff = 69%
GT Fuel Compress Pow = 5.0% %GT Gross Pow
BD Fraction = 3.0% of steam
-
8/2/2019 AIChE 2011 Cogen Screening 05
11/21
21/39Cogen Screening & Targeting for Improved Performance
Case Study
Results 1) Boilers Only
i Typically the reference case as simplest and lowest-capex design
4 All power from external grid, note de-aeration steam for process boilers
423.7 MMBtu/hr
326.8 klb/hr
HP 400.0 psig 644. 5 F
448. 2 F -179.9 MMBtu/hr
59.52 471.4 klb/hr -144.6 klb/hr
MP 250.0 psig 625. 6 F
406. 0 F 248.9 MMBtu/hr
34.26 271.3 klb/hr 200.1 klb/hr
LP 50.0 psig 598. 6 F
Dea Steam 297. 7 F 255.0 MMBtu/hr
66.3 klb/hr 205.0 klb/hr
LD
LD
BO
LDLD
OK: Steam is being supplied to the ProcessOnsite Pow = -0.5 MW
Power Import = 36.5 MW
Power Cost = 18.6 MM$/yr
Net Steam Duty = 324.0 MMBtu/hr
Net Process Stm = 260.5 klb/hr
Fuel Input = 423.7 MMBtu/hr
Fuel Cost = 25.5 MM$/yr
Cooling Duty = 0.0 MMBtu/hr
Desal Potential = 0.0 klb/hr
Cool Net Cost= 0.00 MM$/yr
Onsite CO2 = 219.0 kton/yr
Extern CO2 = 183.6 kton/yr
CO2 Cost = 6.57 MM$/yr
Pow/Heat Ratio = -0.005 Net Pow/Stm
Power Eff = 0.0% %
CHP Eff = 76.5% %
Net Opex = 50.64 MM$/yr
22/39Cogen Screening & Targeting for Improved Performance
Case Study
Results 2) Simple ST Extraction
i Simple extraction enables some onsite power production
4 Steam temps and flows slightly different
OK: Steam is being supplied to the Process
Onsite Pow = 13.0 MW
Power Import = 23.0 MW
Power Cost = 11.8 MM$/yr
Net Steam Duty = 324.0 MMBtu/hr
Net Process Stm = 293.0 klb/hr
Fuel Input = 478.3 MMBtu/hr
Fuel Cost = 28.7 MM$/yr
Cooling Duty = 0.0 MMBtu/hr
Desal Potential = 0.0 klb/hr
Cool Net Cost= 0.00 MM$/yr
Onsite CO2 = 247.3 kton/yr
Extern CO2 = 116.1 kton/yr
CO2 Cost = 7.42 MM$/yr
Pow/Heat Ratio = 0.136 Net Pow/Stm
Power Eff = 9.2% %
CHP Eff = 77.0% %
Net Opex = 47.93 MM$/yr
*All STs shown on the diagram
478.3 MMBtu/hr Temps OK!
368.9 klb/hr
HP 400.0 psig 644. 5 F
448. 2 F -179.9 MMBtu/hr
26.09 206.6 klb/hr -144.6 klb/hr
2.1 MW
MP 250.0 psig 553. 1 F
406. 0 F 248.9 MMBtu/hr
38.76 306.9 klb/hr 0.0 MW 206.6 klb/hr
11.3 MW
LP 50.0 psig 320. 0 F
Dea Steam 297. 7 F 255.0 MMBtu/hr
75.9 klb/hr 231.0 klb/hr
BO
STg
STg
BO
-
8/2/2019 AIChE 2011 Cogen Screening 05
12/21
23/39Cogen Screening & Targeting for Improved Performance
Case Study
Results 3) Enhanced ST Extraction
i Marginally lower opex w higher steam press for power production
4 Additional fuel cancels benefits of extra power
OK: Steam is being supplied to the ProcessOnsite Pow = 16.3 MW
Power Import = 19.7 MW
Power Cost = 10.08 MM$/yr
Net Steam Duty = 324.0 MMBtu/hr
Net Process Stm = 293.0 klb/hr
Fuel Input = 492.9 MMBtu/hr
Fuel Cost = 29.62 MM$/yr
Cooling Duty = 0.0 MMBtu/hr
Desal Potential = 0.0 klb/hr
Cool Net Cost= 0.00 MM$/yr
Onsite CO2 = 254.8 kton/yr
Extern CO2 = 99.4 kton/yr
CO2 Cost = 7.64 MM$/yr
Pow/Heat Ratio = 0.171 Net Pow/Stm
Power Eff = 11.3% %
CHP Eff = 77.0% %
Net Opex = 47.34 MM$/yr
*STs expanding process steam surplus to LP not shown
492.9 MMBtu/hr Temps OK!
368.9 klb/hr
VHP 600.0 psig 725. 8 F
488. 9 F 0.0 MMBtu/hr
0.00 0.0 klb/hr 0.0 klb/hr
0.0 MW
HP 400.0 psig 639. 2 F
448. 2 F -179.9 MMBtu/hr
26.13 207.0 klb/hr 5.2 MW -145.0 klb/hr
4.1 MW
MP 250.0 psig 549. 4 F
406. 0 F 248.9 MMBtu/hr
20.45 162.0 klb/hr 0.0 MW 207.0 klb/hr
7.4 MW
LP 50.0 psig 320. 0 F
Dea Steam 297. 7 F 255.0 MMBtu/hr
75.9 klb/hr 231.0 klb/hr
BO
STg
STg
STg
BO
24/39Cogen Screening & Targeting for Improved Performance
Case Study
Results 4) Enhanced ST Extraction + Condensing
i Extra steam expanded all the way to condensing
4 Higher opex as fuel/emissions costs offset savings in power
OK: Steam is being supplied to the Process
Onsite Pow = 29.6 MW
Power Import = 6.4 MW
Power Cost = 3.26 MM$/yr
Net Steam Duty = 324.0 MMBtu/hr
Net Process Stm = 293.0 klb/hr
Fuel Input = 667.6 MMBtu/hr
Fuel Cost = 40.12 MM$/yr
Cooling Duty = 97.2 MMBtu/hr
Desal Potential = 0.0 klb/hr
Cool Net Cost= 0.43 MM$/yr
Onsite CO2 = 345.2 kton/yr
Extern CO2 = 32.1 kton/yr
CO2 Cost = 10.36 MM$/yr
Pow/Heat Ratio = 0.312 Net Pow/Stm
Power Eff = 15.1% %
CHP Eff = 63.7% %
Net Opex = 54.16 MM$/yr
*STs expanding process steam surplus to LP not shown
667.6 MMBtu/hr Temps OK!
499.8 klb/hr
VHP 600.0 psig 725. 8 F
488. 9 F 0.0 MMBtu/hr
0.00 0.0 klb/hr 0.0 klb/hr
0.0 MW
HP 400.0 psig 639. 2 F
448. 2 F -179.9 MMBtu/hr
26.13 207.0 klb/hr 5.2 MW -145.0 klb/hr
4.1 MW
MP 250.0 psig 549. 4 F
406. 0 F 248.9 MMBtu/hr
36.97 292.8 klb/hr 0.0 MW 207.0 klb/hr
13.4 MW
LP 50.0 psig 320. 0 F
Dea Steam 297. 7 F 255.0 MMBtu/hr
96.3 klb/hr 110.5 klb/hr 231.0 klb/hr
7.6 MW
VP 0.597 psig
85.0 F 97.2 MMBtu/hr
STg
BO
STg
STg
STg
STg
-
8/2/2019 AIChE 2011 Cogen Screening 05
13/21
25/39Cogen Screening & Targeting for Improved Performance
246.4 MMBtu/hr 96.2 / 231.9 MMBtu/hr Temps OK!
184.5 klb/hr 22.8 MW
VHP 600.0 psig 184.5 klb/hr 725.8 F
488.9 F 0.0 MMBtu/hr
0.00 0.0 klb/hr 0.0 klb/hr
0.0 MW
HP 400.0 psig 639.2 F
448.2 F -179.9 MMBtu/hr
26.13 207.0 klb/hr 5.2 MW -145.0 klb/hr
4.1 MW
MP 250.0 psig 549.4 F
406.0 F 248.9 MMBtu/hr
20.45 162.0 klb/hr 0.0 MW 207.0 klb/hr
7.4 MW
LP 50.0 psig 320.0 F
Dea Steam 297.7 F 255.0 MMBtu/hr
75.9 klb/hr 231.0 klb/hr
BOGTg
WHB
STg
STg
STg
Case Study
Results 5) Boiler + GT w SF-HRSG
i Opex decreases as boiler steam share is reduced (transition to pow export)
4 GT+SF-HRSG is more efficient to produce steam and power than BO+ST
OK: Steam is being supplied to the ProcessOnsite Pow = 38.0 MW
Power Import = -2.0 MW
Power Cost = -1.00 MM$/yr
Net Steam Duty = 324.0 MMBtu/hr
Net Process Stm = 293.0 klb/hr
Fuel Input = 574.5 MMBtu/hr
Fuel Cost = 34.53 MM$/yr
Cooling Duty = 0.0 MMBtu/hr
Desal Potential = 0.0 klb/hr
Cool Net Cost= 0.00 MM$/yr
Onsite CO2 = 297.0 kton/yr
Extern CO2 = -9.8 kton/yr
CO2 Cost = 8.91 MM$/yr
Pow/Heat Ratio = 0.400 Net Pow/Stm
Power Eff = 22.5% %
CHP Eff = 78.9% %
Net Opex = 42.44 MM$/yr
*STs expanding process steam surplus to LP not shown
26/39Cogen Screening & Targeting for Improved Performance
Case Study
Results 6) Boiler + GT w SF-HRSG + Condensing
i GT+HRSG reduces opex, but BO+CT is not cost-effective
4 Opex varies with boiler steam share and % duct firing in HRSG
OK: Steam is being supplied to the Process
Onsite Pow = 59.5 MW
Power Import = -23.5 MW
Power Cost = -12.02 MM$/yr
Net Steam Duty = 324.0 MMBtu/hr
Net Process Stm = 293.0 klb/hr
Fuel Input = 780.2 MMBtu/hr
Fuel Cost = 46.89 MM$/yr
Cooling Duty = 97.2 MMBtu/hr
Desal Potential = 0.0 klb/hr
Cool Net Cost= 0.43 MM$/yr
Onsite CO2 = 403.4 kton/yr
Extern CO2 = -118.6 kton/yr
CO2 Cost = 12.10 MM$/yr
Pow/Heat Ratio = 0.627 Net Pow/Stm
Power Eff = 26.0% %
CHP Eff = 67.6% %
Net Opex = 47.39 MM$/yr
*STs expanding process steam surplus to LP not shown
333.8 MMBtu/hr 130.3 / 316.1 MMBtu/hr Temps OK!
249.9 klb/hr 31.5 MW
VHP 600.0 psig 249. 9 k lb/ hr 725. 8 F
488. 9 F 0.0 MMBtu/hr
0.00 0.0 klb/hr 0.0 klb/hr
0.0 MW
HP 400.0 psig 639. 2 F
448. 2 F -179.9 MMBtu/hr
26.13 207.0 klb/hr 5.2 MW -145.0 klb/hr
4.1 MW
MP 250.0 psig 549. 4 F
406. 0 F 248.9 MMBtu/hr
36.97 292.8 klb/hr 0.0 MW 207.0 klb/hr
13.4 MW
LP 50.0 psig 320. 0 F
Dea Steam 297. 7 F 255.0 MMBtu/hr
184.5 klb/hr 110.5 klb/hr 231.0 klb/hr
10.1 MW
VP 0.597 psia
85.0 F 129.6 MMBtu/hr
BO
GTg
WHB
STg
STg
STg
STg
-
8/2/2019 AIChE 2011 Cogen Screening 05
14/21
27/39Cogen Screening & Targeting for Improved Performance
Case Study
Results 7) GT w SF-HRSG + Condensing
i Lower opex without boilers, but condensing still impacts opex
4 Opex varies with condensing duty and % duct firing in HRSG
OK: Steam is being supplied to the ProcessOnsite Pow = 98.0 MW
Power Import = -62.0 MW
Power Cost = -31.64 MM$/yr
Net Steam Duty = 324.0 MMBtu/hr
Net Process Stm = 293.0 klb/hr
Fuel Input = 966.4 MMBtu/hr
Fuel Cost = 58.08 MM$/yr
Cooling Duty = 129.6 MMBtu/hr
Desal Potential = 0.0 klb/hr
Cool Net Cost= 0.57 MM$/yr
Onsite CO2 = 499.7 kton/yr
Extern CO2 = -312.2 kton/yr
CO2 Cost = 14.99 MM$/yr
Pow/Heat Ratio = 1.032 Net Pow/Stm
Power Eff = 34.6% %
CHP Eff = 68.1% %
Net Opex = 41.99 MM$/yr
*STs expanding process steam surplus to LP not shown
260.6 / 628.2 MMBtu/hr Temps OK!
61.9 MW
VHP 600.0 psig 499. 8 k lb/ hr 725. 8 F
488. 9 F 0.0 MMBtu/hr
0.00 0.0 klb/hr 0.0 klb/hr
0.0 MW
HP 400.0 psig 639. 2 F
448. 2 F -179.9 MMBtu/hr
26.13 207.0 klb/hr 5.2 MW -145.0 klb/hr
4.1 MW
MP 250.0 psig 549. 4 F
406. 0 F 248.9 MMBtu/hr
36.97 292.8 klb/hr 0.0 MW 207.0 klb/hr
13.4 MW
LP 50.0 psig 320. 0 F
Dea Steam 297. 7 F 255.0 MMBtu/hr
96.3 klb/hr 110.5 klb/hr 231.0 klb/hr
7.6 MW
VP 0.597 psia
85.0 F 97.2 MMBtu/hr
GTg
WHB
STg
STg
STgSTg
STg
28/39Cogen Screening & Targeting for Improved Performance
Case Study
Results 8) GT w SF-HRSG
i Eliminating boilers and condensing reduces opex even further
4 Opex varies with % duct firing in HRSG
OK: Steam is being supplied to the Process
Onsite Pow = 59.6 MW
Power Import = -23.6 MW
Power Cost = -12.07 MM$/yr
Net Steam Duty = 324.0 MMBtu/hr
Net Process Stm = 293.0 klb/hr
Fuel Input = 656.2 MMBtu/hr
Fuel Cost = 39.43 MM$/yr
Cooling Duty = 0.0 MMBtu/hr
Desal Potential = 0.0 klb/hr
Cool Net Cost= 0.00 MM$/yr
Onsite CO2 = 339.3 kton/yr
Extern CO2 = -119.1 kton/yr
CO2 Cost = 10.18 MM$/yr
Pow/Heat Ratio = 0.628 Net Pow/Stm
Power Eff = 31.0% %
CHP Eff = 80.4% %
Net Opex = 37.54 MM$/yr
*STs expanding process steam surplus to LP not shown
192.4 / 463.8 MMBtu/hr Temps OK!
45.7 MW
VHP 600.0 psig 368. 9 k lb/ hr 725. 8 F
488.9 F 0.0 MMBtu/hr
0.00 0.0 klb/hr 0.0 klb/hr
0.0 MW
HP 400.0 psig 639.2 F
448.2 F -179.9 MMBtu/hr
26.13 207.0 klb/hr 5.2 MW -145.0 klb/hr
4.1 MW
MP 250.0 psig 549.4 F
406.0 F 248.9 MMBtu/hr
20.45 162.0 klb/hr 0.0 MW 207.0 klb/hr
7.4 MW
LP 50.0 psig 320.0 F
Dea Steam 297.7 F 255.0 MMBtu/hr
75.9 klb/hr 231.0 klb/hr
GTg
WHB
STg
STg
STg
-
8/2/2019 AIChE 2011 Cogen Screening 05
15/21
29/39Cogen Screening & Targeting for Improved Performance
Case Study
Results 9) GT w UF-HRSG
i Unfired HRSG allows installing a larger GT for additional power
4 >Power Eff, but
-
8/2/2019 AIChE 2011 Cogen Screening 05
16/21
31/39Cogen Screening & Targeting for Improved Performance
Case Study
Results 11) GT w UF-HRSG + Bypass
i GT size fully decoupled from steam demands and condensing
4 More GT output, but Opex
OK: Steam is being supplied to the ProcessOnsite Pow = 203.0 MWe
Power Import = -167.0 MWe
Power Cost = -85.24 MM$/yr
Net Steam Duty = 324.0 MMBtu/hr
Net Process Stm = 293.0 klb/hr
Fuel Input = 1995.7 MMBtu/hr
Fuel Cost = 119.93 MM$/yr
Cooling Duty = 0.0 MMBtu/hr
Desal Potential = 0.0 klb/hr
Cool Net Cost= 0.00 MM$/yr
Onsite CO2 = 1031.8 kton/yr
Extern CO2 = -841.0 kton/yr
CO2 Cost = 30.96 MM$/yr
Pow/Heat Ratio = 2.137 Net Pow/Stm
Power Eff = 34.7% %
CHP Eff = 50.9% %
Net Opex = 65.65 MM$/yr
*STs expanding process steam surplus to LP not shown
Bpass = 50.0% 0.0 / 1995.7 MMBtu/hr Temps OK!
196.5 MW
VHP 600.0 psig 368. 9 k lb/ hr 725. 8 F
488. 9 F 0.0 MMBtu/hr
0.00 0.0 klb/hr 0.0 klb/hr
0.0 MW
HP 400.0 psig 639. 2 F
448. 2 F -179.9 MMBtu/hr
26.13 207.0 klb/hr 5.2 MW -145.0 klb/hr
4.1 MW
MP 250.0 psig 549. 4 F
406. 0 F 248.9 MMBtu/hr
20.45 162.0 klb/hr 0.0 MW 207.0 klb/hr
7.4 MW
LP 50.0 psig 320. 0 F
Dea Steam 297. 7 F 255.0 MMBtu/hr
75.9 klb/hr 0.0 klb/hr 231.0 klb/hr
0.0 MW
VP 0.597 psia
85.0 F 0.0 MMBtu/hr
GTg
WHB
STg
STg
STgSTg
STg
32/39Cogen Screening & Targeting for Improved Performance
Case Study
Results 12) GT w UF-HRSG + Bypass + Condensing
i Even larger GT for the same %bypass, but penalty from condensing too
4 A way to produce more power if it were cost effective
OK: Steam is being supplied to the Process
Onsite Pow = 282.5 MW
Power Import = -246.5 MW
Power Cost = -125.85 MM$/yr
Net Steam Duty = 324.0 MMBtu/hr
Net Process Stm = 293.0 klb/hr
Fuel Input = 2703.3 MMBtu/hr
Fuel Cost = 162.45 MM$/yr
Cooling Duty = 97.2 MMBtu/hr
Desal Potential = 0.0 klb/hr
Cool Net Cost= 0.43 MM$/yr
Onsite CO2 = 1397.7 kton/yr
Extern CO2 = -1241.7 kton/yr
CO2 Cost = 41.93 MM$/yr
Pow/Heat Ratio = 2.975 Net Pow/Stm
Power Eff = 35.7% %
CHP Eff = 47.6% %
Net Opex = 78.96 MM$/yr
*STs expanding process steam surplus to LP not shown
Bpass = 50.0%
0.0 MMBtu/hr 0.0 / 2703.3 MMBtu/hr Temps OK!
0.0 klb/hr 266.2 MW
VHP 600.0 psig 499.8 klb/hr 725.8 F
488.9 F 0.0 MMBtu/hr
0.00 0.0 klb/hr 0.0 klb/hr
0.0 MW
HP 400.0 psig 639.2 F
448.2 F -179.9 MMBtu/hr
26.13 207.0 klb/hr 5.2 MW -145.0 klb/hr
4.1 MW
MP 250.0 psig 549.4 F
406.0 F 248.9 MMBtu/hr
36.97 292.8 klb/hr 0.0 MW 207.0 klb/hr
13.4 MW
LP 50.0 psig 320.0 F
Dea Steam 297.7 F 255.0 MMBtu/hr
96.3 klb/hr 110.5 klb/hr 231.0 klb/hr
7.6 MW
VP 0.597 psia
85.0 F 97.2 MMBtu/hr
GTg
WHB
STg
STg
STg
STg
BO
-
8/2/2019 AIChE 2011 Cogen Screening 05
17/21
33/39Cogen Screening & Targeting for Improved Performance
Case Study
Performance Results: Improved R-Curves
i Conventional R-curves only for limited configurations and equipment sizes
4 Proposed approach customizable to represent different systems
i Portraying the efficiency trends of (practically) all options
R-Curves for diff CHP Configurations
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
Power/Heat Ratio, MWe/MWth
Efficiency CHP Efficiency
Power Efficiency
BO+ST
BO+GT+SF+ST
BO+ST+CT
GT+SF+STGT+SF+ST+CT
GT+UF+ST+CT
GT+UF+ST+Bpass
34/39Cogen Screening & Targeting for Improved Performance
Case Study
Performance Results: Improved R-Curves
i Depending on specific site conditions, trends can be different
4 Configurations and sizes will affect site performance
4 E.g. condensing reduces CHP efficiency (but improves power efficiency)
R-Curves for diff CHP Configurations
GT+SF+ST
BO+GT+SF+STBO+ST
BO+ST+CT
GT+SF+ST+CT GT+UF+ST+CT
GT+UF+ST+Bpass
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
Power/Heat Ratio, MWe/MWth
CHP
Efficiency
-
8/2/2019 AIChE 2011 Cogen Screening 05
18/21
35/39Cogen Screening & Targeting for Improved Performance
Case Study
Economic Results: E-Curves
i Efficiency not always equivalent to cost-effectiveness
4 Decisions should be also supported by economics
i Note the divergent trends in fuel and power costs
Economic Curves for diff CHP Configurations
-200
-150
-100
-50
0
50
100
150
200
0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50
Power/Heat Ratio, MWe/MWth
A
nnualCost,MM$/yr
Tot Cost
Fuel Cost
Pow Cost
BO+ST
BO+GT+SF+STBO+ST+CT
GT+SF+ST
GT+SF+ST+CT
GT+UF+ST+CTGT+UF+ST+Bpass
36/39Cogen Screening & Targeting for Improved Performance
Case Study
Fuel Chargeable to Power: Fuel-Power Curves
i How much extra fuel to produce additional power
4 Onsite cost of producing power
BO+BST
BO+GT+100%SF+BST
GT+50%SF+BST
BO+BST+CST
GT+100%SF+BST
GT+100%SF+BST+CST
GT+0%UF+BSTGT+0%UF+BST+CST
GT+0%UF+BST+Bpass
0
10
20
30
40
50
60
70
80
90
0.0 100.0 200.0 300.0 400.0 500.0 600.0 700.0 800.0
ExtraPowerCost,$/MWh
Onsite Power, MWe
Extra Power Cost for different CHP ConfigurationsBO = Stand Alone
Boiler
BST = Back-PressSteam Turbine
CST = CondensingSteam Turbine
GT = Gas Turbine100%SF = Fully fired
HRSG0%UF = Unfired HRSGBpass = Bypass HRSG
GT Exhaust
Note 1) BO+BST+CST may show aconstant value since BO+BST is taken
as reference
Note 2) For lower site power, extra costdrops down t o zero
-
8/2/2019 AIChE 2011 Cogen Screening 05
19/21
37/39Cogen Screening & Targeting for Improved Performance
Case Study
Economic Results: E-Curves
i This approach provides insight to the design process
4 E.g. even if efficiency is reduced, condensing can be cost-effective
i Note that min Opex happens when eliminating duct firing
4 Largest GT size without bypassing the HRSGEconomic Curves for diff CHP Configurations
GT+SF+STBO+GT+SF+ST
BO+ST
BO+ST+CT
GT+SF+ST+CT
GT+UF+ST+CT
GT+UF+ST+Bpass
0
10
20
30
40
50
60
70
80
90
0.00 0.50 1.00 1.50 2.00 2.50 3.00
Power/Heat Ratio, MWe/MWth
AnnualCost,MM$/yr
38/39Cogen Screening & Targeting for Improved Performance
Case Study
CO2 Emissions: CO2-Curves
i To identify the design options that minimize CO2 emissions
4 E.g. impact of CO2 taxes or cost to reduce the emissions
i Trends in onsite and overall CO2 footprint
CO2 Curves for diff CHP Configurations
-1500
-1000
-500
0
500
1000
1500
0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50
Power/Heat Ratio, MWe/MWth
CO2Emissions,
kton/yr
Onsite CO2
Extern CO2
Tot CO2
BO+ST
BO+GT+SF+STBO+ST+CT
GT+SF+ST
GT+SF+ST+CT
GT+UF+ST+CTGT+UF+ST+Bpass
-
8/2/2019 AIChE 2011 Cogen Screening 05
20/21
39/39Cogen Screening & Targeting for Improved Performance
Case Study
CO2 Emissions: CO2-Curves
i Trends can significantly change with individual factors
4 Overall emissions vary with internal and external power efficiencies
CO2 Curves for diff CHP Configurations
GT+SF+ST
BO+GT+SF+ST
BO+ST
BO+ST+CT
GT+SF+ST+CT
GT+UF+ST+CT
GT+UF+ST+Bpass
0
50
100
150
200
250
300
350
400
450
500
0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50
Power/Heat Ratio, MWe/MWth
CO
2Emissions,
kton/yr
Tot CO2
40/39Cogen Screening & Targeting for Improved Performance
Case Study
CO2 Emmissions: CO2-Curves
i Impact of increasing external efficiency from 35% to 50%
4 In this case, loading the CT increases overall CO2
4 Less emissions by importing power from a more efficient external source
CO2 Curves for diff CHP Configurations
GT+SF+ST
BO+GT+SF+STBO+ST
BO+ST+CT
GT+SF+ST+CT
GT+UF+ST+CT
GT+UF+ST+Bpass
0
100
200
300
400
500
600
700
0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50
Power/Heat Ratio, MWe/MWth
CO2Emissions,
kton/yr
Tot CO2
-
8/2/2019 AIChE 2011 Cogen Screening 05
21/21
41/39Cogen Screening & Targeting for Improved Performance
Conclusions & Future Work
h An integrated approach for screening CHP options have been proposed
4 Blending standard calculations with novel features
h Consistent comparison framework to quickly identify promising options
4 Effect of different configurations and equipment sizes on performance
4 Performance: Fuel usage (efficiency), economics, CO2 emissions (E/E/E)
4 Alternatives can be evaluated side-by-side on a consistent basis
4 Can be tailored to represent a specific site or type of plant
h This approach guides the design process in a systematic way
4 Document and support decisions (in the right direction), rather than trial-error
h Screening tool for new designs / Targeting tool for existing sites
4 Best configurations for a new design / best an existing site can achieve
h Still a work in progress:
4 Need more cases to be tested
4 Include other options (desalination, capex)
CHP Screening for Improved
Performance and CO2 Reduction:Revisiting the R-Curves
S i M ti 2010
By Oscar Aguilar
San Antonio, TX March 2010