module 14. “life cycle assessment (lca)” 4 steps of … steps of lca, approaches, software,...

PIECEPIECEProgramProgram forfor NorthNorth AmericanAmerican MobilityMobility In In HigherHigher EducationEducation

MODULE 14. MODULE 14. ““Life Cycle Assessment (LCA)Life Cycle Assessment (LCA)””4 steps of LCA, approaches, software, databases, 4 steps of LCA, approaches, software, databases, subjectivity, sensitivity analysis, application to a subjectivity, sensitivity analysis, application to a classic example. classic example.

Module 14 – Life Cycle Assessment 22

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Tier IIIOpen-ended problem


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What are the prerequisites for this tier?What are the prerequisites for this tier?

It is further assumed that students already have an introductoryIt is further assumed that students already have an introductory--

level background in Life Cycle Assessment (LCA) (from Tier I andlevel background in Life Cycle Assessment (LCA) (from Tier I and

Tier II) and the basic knowledge in petrochemical processes, sucTier II) and the basic knowledge in petrochemical processes, such h

as would normally be part of any undergraduate engineering as would normally be part of any undergraduate engineering

curriculum.curriculum.

Prerequisites for tierPrerequisites for tier


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What is the purpose of this module?What is the purpose of this module?

OpenOpen--Ended Design ProblemEnded Design Problem. Is comprised of an open. Is comprised of an open--

ended problem to solve realended problem to solve real--life application of LCA to life application of LCA to

the oil and gas sector. The global aim of that problem is the oil and gas sector. The global aim of that problem is

to quantify the total environmental benefits and to quantify the total environmental benefits and

drawback of a process. drawback of a process.

Statement of intentStatement of intent

A1

A1 "to solve a" instead of "of a solve"ANTONIO; 06-janv.-05


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Spath Spath andand Mann. (2001) Mann. (2001) ””Life Cycle Assessment of Hydrogen Production via Life Cycle Assessment of Hydrogen Production via

Natural Gas Steam ReformingNatural Gas Steam Reforming““. National Renewable Energy Laboratory.. National Renewable Energy Laboratory.

SpathSpath and Mann. (1999) and Mann. (1999) ““Life Cycle Assessment of CoalLife Cycle Assessment of Coal--fired Power fired Power

ProductionProduction””. National Renewable Energy Laboratory.. National Renewable Energy Laboratory.

Mann and Mann and SpathSpath. (1997) . (1997) ““Life Cycle Assessment of Biomass Gasification Life Cycle Assessment of Biomass Gasification

CombinedCombined--Cycle SystemCycle System””. National Renewable Energy Laboratory.. National Renewable Energy Laboratory.

RojeyRojey A., A., MinkkinenMinkkinen A., Arlie J.P. and A., Arlie J.P. and LebasLebas E. E. ““Combined Production of Combined Production of

Hydrogen, Clean Power and Quality FuelsHydrogen, Clean Power and Quality Fuels””. . InstitutInstitut FranFranççaisais dudu PPéétroletrole (IFP).(IFP).

ReferencesReferences


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D. Gray, G. Tomlinson, D. Gray, G. Tomlinson, ““Opportunities For Petroleum Coke Gasification Under Tighter Opportunities For Petroleum Coke Gasification Under Tighter

Sulfur Limits For Transportation Fuels,Sulfur Limits For Transportation Fuels,”” Presented at the Gasification Technologies Presented at the Gasification Technologies

Conference, San Francisco, California, October 8Conference, San Francisco, California, October 8––11, 200011, 2000

H. Baumann, A.M. Tillman(2004). H. Baumann, A.M. Tillman(2004). ‘’‘’The hitch The hitch HickerHicker’’ss Guide to LCA. An orientation in life Guide to LCA. An orientation in life

cycle assessment methodology and applicationcycle assessment methodology and application’’’’. . StudentlitteraturStudentlitteratur AB. Lund, Sweden AB. Lund, Sweden

TheThe EnvironmentalEnvironmental FoundationFoundation BellonaBellona :: http://http://www.bellona.nowww.bellona.no/en/energy/en/energy

University of University of NewbrunswickNewbrunswick (Canada) ((Canada) (PetroleumPetroleum andand Natural Gas Natural Gas ProcessingProcessing):):

http://www.unb.ca/che/che5134/smr.htmhttp://www.unb.ca/che/che5134/smr.htm

ReferencesReferences


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Tier III is broken in six parts:Tier III is broken in six parts:

•• Description of the context: Hydrogen production via natural gas Description of the context: Hydrogen production via natural gas steam reformingsteam reforming

•• Problem statementProblem statement•• Statement of the intentStatement of the intent•• Report StructureReport Structure•• RecommendationsRecommendations•• IndexIndex

Unlike the previous two sections, this section does not have a Unlike the previous two sections, this section does not have a quiz. The student must interpret the results of the above work quiz. The student must interpret the results of the above work and elaborate a succinct project report (15 and elaborate a succinct project report (15 -- 20 pages).20 pages).

Tier III: ContentTier III: Content


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Metric units of measure are used. Therefore, material consumptiMetric units of measure are used. Therefore, material consumption is reported in on is reported in units based on the gram (e.g., kilogram or metric units based on the gram (e.g., kilogram or metric tonnetonne), energy consumption ), energy consumption based on the joule (e.g., based on the joule (e.g., kilojoulekilojoule or or megajoulemegajoule), and distance based on the ), and distance based on the meter (e.g., meter). When it can contribute to the understandinmeter (e.g., meter). When it can contribute to the understanding of the analysis, the g of the analysis, the English system equivalent is stated in parenthesis. The metric English system equivalent is stated in parenthesis. The metric units used for each units used for each parameter are given below, with the corresponding conversion to parameter are given below, with the corresponding conversion to English units.English units.

Mass:Mass: kilogram (kg) = 2.205 poundskilogram (kg) = 2.205 poundsMetric Metric tonnetonne (T) = 1.102 ton (t)(T) = 1.102 ton (t)

Distance: Distance: Meter (m) = 6200 mile = 3281 feetMeter (m) = 6200 mile = 3281 feet

Area: Area: hectare (ha) = 10,000 m2 = 2.47 acreshectare (ha) = 10,000 m2 = 2.47 acres

Volume: Volume: cubic meter (mcubic meter (m33) = 264.17 gallons) = 264.17 gallonsnormal cubic meters (Nmnormal cubic meters (Nm33) = 0.02628 standard cubic feet () = 0.02628 standard cubic feet (scfscf) at a standard ) at a standard temperature & pressure of 15.6temperature & pressure of 15.6°°C (60C (60°°F) and 101.4 F) and 101.4 kPakPa (14.7 (14.7 psipsi), ), respectivelyrespectively

Tier III: Units of measuTier III: Units of measur

A2

A2 megagram?

meter instead of km

what is 1 x 106 g?ANTONIO; 06-janv.-05


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Pressure: Pressure: kilopascals (kilopascals (kPakPa) = 0.145 pounds per square inch) = 0.145 pounds per square inch

Energy:Energy: kilojoulekilojoule (kJ) = 1,000 Joules (J) = 0.9488 Btu(kJ) = 1,000 Joules (J) = 0.9488 BtuGigajouleGigajoule (GJ) = 0.9488 (GJ) = 0.9488 MMBtuMMBtu (million Btu)(million Btu)TerajouleTerajoule ((TjTj) = 1.0 x 10) = 1.0 x 1099 Joules (J)Joules (J)kilowattkilowatt--hour (kWh) = 3,414.7 Btuhour (kWh) = 3,414.7 BtuGigawattGigawatt--hour (hour (GWhGWh) = 3.4 x 109 Btu) = 3.4 x 109 Btu

Power: Power: megawatt (MW) = 1 x 106 J/smegawatt (MW) = 1 x 106 J/s

Temperature:Temperature: °°C = (C = (°°F F -- 32)/1.832)/1.8

Hydrogen Equivalents:Hydrogen Equivalents:

1 kg H1 kg H22 = 423.3 = 423.3 scfscf gas = 11.126 Nmgas = 11.126 Nm33 gasgas

Tier III: Units of measuTier III: Units of measur

A3

A3 tera joule instead of tetra--ANTONIO; 06-janv.-05


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Btu Btu -- British thermal unitsBritish thermal unitsCO2CO2--equivalenceequivalence-- Expression of the GWP in terms of CO2 for the following three Expression of the GWP in terms of CO2 for the following three

components CO2, CH4, N2O, based on IPCC weighting factorscomponents CO2, CH4, N2O, based on IPCC weighting factorsEIA EIA -- Energy Information AdministrationEnergy Information AdministrationGWP GWP -- global warming potentialglobal warming potentialHHV HHV -- higher heating valuehigher heating valueHTS HTS -- high temperature shifthigh temperature shiftIPCCIPCC-- Intergovernmental Panel on Climate ChangeIntergovernmental Panel on Climate ChangekWh kWh -- kilowattkilowatt--hour (denotes energy)hour (denotes energy)LCA LCA -- life cycle assessmentlife cycle assessmentLHV LHV -- lower heating valuelower heating valueLTS LTS -- low temperature shiftlow temperature shiftMMSFCD MMSFCD -- million standard cubic feet per daymillion standard cubic feet per dayMW MW -- megawatt (denotes power)megawatt (denotes power)N2O N2O -- nitrous oxidenitrous oxideNm3 Nm3 -- normal cubic metersnormal cubic metersNMHCsNMHCs -- nonnon--methane hydrocarbonsmethane hydrocarbonsNOxNOx -- nitrogen oxides, excluding nitrous oxide (N2O)nitrogen oxides, excluding nitrous oxide (N2O)NREL NREL -- National Renewable Energy LaboratoryNational Renewable Energy LaboratoryPSA PSA -- pressure swing adsorptionpressure swing adsorptionSMR SMR -- steam methane reformingsteam methane reformingSOxSOx -- sulfur oxides, including the most common form of airborne sulfursulfur oxides, including the most common form of airborne sulfur, SO2, SO2Stressor Stressor -- A term that collectively defines emissions, resource consumptionA term that collectively defines emissions, resource consumption, and , and

energy use; a substance or activity that results in a change to energy use; a substance or activity that results in a change to the the natural environmentnatural environment

Stressor category Stressor category -- A group of stressors that defines possible impactsA group of stressors that defines possible impactswt% wt% -- percentage by weightpercentage by weight

Tier III: Abbreviations and TeTier III: Abbreviations and Te


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1.1. Description of the context: Hydrogen production via natural gas Description of the context: Hydrogen production via natural gas steam steam reformingreforming

2.2. Problem statementProblem statement3.3. Statement of the intentStatement of the intent

a.a. System boundariesSystem boundariesb.b. Major assumptionsMajor assumptionsc.c. DataData

4.4. Report StructureReport Structure5.5. RecommandationsRecommandations6.6. IndexIndex

Tier III: OutlineTier III: Outline


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1.1. Description of the context: Hydrogen production via natural gas Description of the context: Hydrogen production via natural gas steam reformingsteam reforming



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1.1. Description of the context: Hydrogen production Description of the context: Hydrogen production via natural gas steam reformingvia natural gas steam reforming

1.1. Hydrogen (H1.1. Hydrogen (H22))

HydrogenHydrogen is used in a is used in a numbernumber of industrial applications, with todayof industrial applications, with today’’s largest consumers s largest consumers being ammonia production facilities (40.3 %), oil refineries (37being ammonia production facilities (40.3 %), oil refineries (37.3%), and methanol .3%), and methanol production plants (10.0%). Because such large quantities of hydrproduction plants (10.0%). Because such large quantities of hydrogen are required in ogen are required in these instances, the hydrogen is generally produced by the consuthese instances, the hydrogen is generally produced by the consumer, and the most mer, and the most common method is common method is steam reforming of natural steam reforming of natural gas.gas. The figure below shows a The figure below shows a simplified flowsheet of the process utilised in this context forsimplified flowsheet of the process utilised in this context for hydrogen production.hydrogen production.

A4

A4 Number, not numeral

We need a diagram to complement the explanation, like the one in page 24ANTONIO; 06-janv.-05


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1.2. The process1.2. The process

Hydrogen can be produced from Hydrogen can be produced from natural gasnatural gas, oil or coal. , oil or coal. Synthesis gas Synthesis gas production is a production is a key step, as it gives access to a wide range of options. Syntheskey step, as it gives access to a wide range of options. Synthesis gas which is formed is gas which is formed mainly by a mixture of CO and H2 is obtained either by steammainly by a mixture of CO and H2 is obtained either by steam--reforming, in the case of reforming, in the case of natural gas or by partial oxidation. Steam methane reforming isnatural gas or by partial oxidation. Steam methane reforming is the most common and the most common and least expensive method of producing hydrogen. About half of the least expensive method of producing hydrogen. About half of the world's hydrogen is world's hydrogen is produced from produced from SMRSMR ((GaudernackGaudernack, 1998). The process can be used also with other , 1998). The process can be used also with other light hydrocarbon light hydrocarbon feedstocksfeedstocks, such as ethane and naphtha. The process is endothermic , such as ethane and naphtha. The process is endothermic and synthesis gas is typically produced in a tubular reformer fuand synthesis gas is typically produced in a tubular reformer furnace.rnace.


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Inlet temperatures are within the range 450Inlet temperatures are within the range 450--650650°°C and the product gas leaves the C and the product gas leaves the reformer at 700reformer at 700--950950°°C, depending on the applications (C, depending on the applications (RostrupRostrup--Nielsen, 1993). The Nielsen, 1993). The desulphurizeddesulphurized feedstock is mixed with process steam and reacted over a nickelfeedstock is mixed with process steam and reacted over a nickel based based catalyst contained in high alloy steel tubes. Although the plancatalyst contained in high alloy steel tubes. Although the plant requires some stream t requires some stream for the reforming and shift reactions, the highly exothermic reafor the reforming and shift reactions, the highly exothermic reactions results in an ctions results in an excess amount of steam produced by the plant. Due to the high excess amount of steam produced by the plant. Due to the high operating operating temperature in the reformer, the reformer effluent contains aboutemperature in the reformer, the reformer effluent contains about 10t 10--15 15 volvol % CO (dry % CO (dry basis). basis). A highA high--temperature shift (HTS) operating at an inlet temperature of 343temperature shift (HTS) operating at an inlet temperature of 343 to 371to 371°°C C makes possible to convert about 80 to 90% of the CO. This step umakes possible to convert about 80 to 90% of the CO. This step uses a catalyst which ses a catalyst which is typically composed of copper oxideis typically composed of copper oxide--zinc oxide on alumina. A zinc oxide on alumina. A Pressure Swing Pressure Swing Adsorption unit (PSA)Adsorption unit (PSA) is used for removing CO and other contaminants present with is used for removing CO and other contaminants present with hydrogen. hydrogen.


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IfIf the CO2 which is present typically at the level of 15the CO2 which is present typically at the level of 15--20% has to be recovered, it may 20% has to be recovered, it may be more appropriate to use a specific step for separating CO2 frbe more appropriate to use a specific step for separating CO2 from hydrogen by om hydrogen by solvent scrubbing. An amine solvent is typically used for such asolvent scrubbing. An amine solvent is typically used for such a separation step. The separation step. The hydrogen thus obtained, can be exported. Refining is presently thydrogen thus obtained, can be exported. Refining is presently the main consumer of he main consumer of hydrogen. It can be used also in a combined cycle for generatinghydrogen. It can be used also in a combined cycle for generating electricity. electricity. Such a scheme provides therefore an attractive option for producSuch a scheme provides therefore an attractive option for producing electricity, without ing electricity, without emitting CO2. Synthesis gas produced during the initial step, caemitting CO2. Synthesis gas produced during the initial step, can also be used for n also be used for producing liquid hydrocarbon fuels, through Fischerproducing liquid hydrocarbon fuels, through Fischer--TropschTropsch synthesis. Thus, it is synthesis. Thus, it is possible to transform any fossil fuel or biomass into hydrogen, possible to transform any fossil fuel or biomass into hydrogen, electricity and liquid electricity and liquid fuels.fuels.


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1.1. Description of the context: Hydrogen production via natural gas Description of the context: Hydrogen production via natural gas steam reformingsteam reforming2.2. Problem statementProblem statement



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2.2. Problem StatementProblem Statement

An oil & gas plant seeks to modernize by looking at 3 process An oil & gas plant seeks to modernize by looking at 3 process options: improving the options: improving the environmental aspects, improving the performance of some units oenvironmental aspects, improving the performance of some units of production to f production to maximize the hydrogen production and finaly to install a better maximize the hydrogen production and finaly to install a better system of electronic system of electronic control of the process.control of the process. Your are the process engineer in this firm. Your boss, the planYour are the process engineer in this firm. Your boss, the plant t manager, wants you to do a study on the manager, wants you to do a study on the thethe total environmental aspects total environmental aspects (quantification and analysis) of producing 48 (quantification and analysis) of producing 48 MMscfdMMscfd of hydrogen via natural gas of hydrogen via natural gas steam reforming for the intern study. In recognition of the facsteam reforming for the intern study. In recognition of the fact that upstream t that upstream processes required for the operation of the Steam Methane Reformprocesses required for the operation of the Steam Methane Reforming (SMR) plant also ing (SMR) plant also produce pollutant and consume energy and natural resources.produce pollutant and consume energy and natural resources.

TheThe data data colletioncolletion and validation have already been done by another engineer. and validation have already been done by another engineer.

A5

A5 not very clear..., which are the 3 options, etcANTONIO; 06-janv.-05


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1.1. Description of the context: Hydrogen production via natural gas Description of the context: Hydrogen production via natural gas steam reformingsteam reforming2.2. Problem statementProblem statement3.3. Statement of the intentStatement of the intent



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1.1. Description of the context: Hydrogen production via natural gas Description of the context: Hydrogen production via natural gas steam reformingsteam reforming2.2. Problem statementProblem statement3.3. Statement of the intent Statement of the intent

a.a. System boundariesSystem boundaries



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3.3. Statement of the intentStatement of the intent

3.1. System boundaries3.1. System boundaries

This LCA should be performed in a cradleThis LCA should be performed in a cradle--toto--grave manner, for this reason, natural gas grave manner, for this reason, natural gas production and distribution, as well as electricity generation, production and distribution, as well as electricity generation, were included in the were included in the system boundaries. The steps associated with obtaining the natursystem boundaries. The steps associated with obtaining the natural gas feedstock are al gas feedstock are drilling/extraction, processing, and pipeline transport. The nexdrilling/extraction, processing, and pipeline transport. The next figure shows the t figure shows the System Boundaries for Hydrogen Production via Natural Gas SteamSystem Boundaries for Hydrogen Production via Natural Gas Steam Reforming.Reforming.

R a w m a te r ia l e x t r a c t io n

R a w m a te r ia l e x t r a c t io n

P r o d u c t io n& d is t r ib u t io no f e le c t r ic ity

P r o d u c t io n& d is t r ib u t io no f e le c t r ic ity

C o n s t r u c t io no f e q u ip m e n tC o n s t r u c t io no f e q u ip m e n t

P r o d u c t io n& d is t r ib u t io no f n a tu r a l g a s


H y d r o g e np r o d u c t io n

p la n t

H y d r o g e np r o d u c t io n

p la n t



N a tu r a l g a sb o ile r

N a tu r a l g a sb o ile r

R e c y c lin gR e c y c lin g

L a n d f i l l in gL a n d f i l l in g

x x x x

XX

EE

E

E

E

E

E

-E

-E

-R M

-E m

R M

R M

R M

R M

R MR M

-R M

- E m

E m

E m

E m

E mE m

E m

E m

M

E = e n e r g yE m = e m is s io n sM = m a te r ia lsR M = r a w m a te r ia ls

A v o id e d o p e r a t io n s


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3.3. Statement of the intentStatement of the intent3.1. System boundaries3.1. System boundaries

For this study, the plant life was set at 20 years with 2 years For this study, the plant life was set at 20 years with 2 years of construction. In year of construction. In year

one, the hydrogen plant begins to operate; plant construction taone, the hydrogen plant begins to operate; plant construction takes place in the two kes place in the two

years prior to this (years negative two and negative one). In yeyears prior to this (years negative two and negative one). In year one the hydrogen ar one the hydrogen

plant is assumed to operate only 45% (50% of 90%) of the time duplant is assumed to operate only 45% (50% of 90%) of the time due to starte to start--up up

activities. In years one through 19, normal plant operation occuactivities. In years one through 19, normal plant operation occurs, with a 90% capacity rs, with a 90% capacity

factor. During the last year the hydrogen plant is decommissionefactor. During the last year the hydrogen plant is decommissioned. Therefore, the d. Therefore, the

hydrogen plant will be in operation 67.5% (75% of 90%) of the lahydrogen plant will be in operation 67.5% (75% of 90%) of the last year.st year.


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a.a. System boundariesSystem boundariesb.b. Major assumptionsMajor assumptions



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3.2. Major assumptions3.2. Major assumptions

A pretreatment on the natural gas is necessary to avoid emposoinA pretreatment on the natural gas is necessary to avoid emposoinment of the catalysts ment of the catalysts with the sulphur. Thewith the sulphur. The H2S is H2S is removedremoved in in a hydrogenation reactor and then in aa hydrogenation reactor and then in a ZnOZnObed.bed. After pretreatment, the natural gas and 2.6 After pretreatment, the natural gas and 2.6 MPaMPa steam are fed to the steam steam are fed to the steam reformer. The resulting synthesis gas is then fed to high temperreformer. The resulting synthesis gas is then fed to high temperature shift (HTS) and ature shift (HTS) and LTS reactors where the water gas shift reaction converts 92% of LTS reactors where the water gas shift reaction converts 92% of the CO into H2.the CO into H2.

Hydrogenation ZnO BedCatalyticSteam

Reforming

HighTemperature

Shift

LowTemperature

Shift

PressureSwing

Adsorption

Natural gas feedstock

Naturalgas fuel

Off-gas

steam

H2 product slipstream

H2

Hydrogenation ZnO BedCatalyticSteam

Reforming

HighTemperature

Shift

LowTemperature

Shift

PressureSwing

Adsorption

Natural gas feedstock

Naturalgas fuel

Off-gas

steam

H2 product slipstream

H2

Hydrogen Plant Block Flow DiagramHydrogen Plant Block Flow Diagram

A6

A6 not very clearANTONIO; 06-janv.-05


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)(6.2)(8.4

requiredenergysteamMPayelectricitenergygasnaturalportedexenergysteamMPahydrogenproductinenergy

+++

The hydrogen is purified (to 99.9% mol.) using a pressure swing The hydrogen is purified (to 99.9% mol.) using a pressure swing adsorption (PSA) adsorption (PSA) unit. The reformer is fueled primarily by the PSA offunit. The reformer is fueled primarily by the PSA off--gas, but a small amount of gas, but a small amount of natural gas is used to supply the balance of the reformer duty. natural gas is used to supply the balance of the reformer duty. The PSA offThe PSA off--gas is gas is comprised of CO2 (47.06 mol%), H2 (24.26 mol%), CH4 (19.59 mol%)comprised of CO2 (47.06 mol%), H2 (24.26 mol%), CH4 (19.59 mol%), CO (7.8 , CO (7.8 mol%), N2 (0.55 mol%), and some water vapor. The steam reformingmol%), N2 (0.55 mol%), and some water vapor. The steam reforming process process produces 4.8 produces 4.8 MPaMPa steam. Electricity is purchased from the grid to operate the pusteam. Electricity is purchased from the grid to operate the pumps mps and compressors. and compressors.

The hydrogen plant energy efficiency is defined as the total eneThe hydrogen plant energy efficiency is defined as the total energy produced by rgy produced by hydrogen plant divided by the total energy into the plant, deterhydrogen plant divided by the total energy into the plant, determines by the following mines by the following formula:formula:

TheThe base case of this analysis assumed that 1.4% of the natural gasbase case of this analysis assumed that 1.4% of the natural gas that is produced that is produced is lost to the atmosphere due to fugitive emissions. is lost to the atmosphere due to fugitive emissions.

A7

A7 overall spelling, determined instead of determines

change font of formula, nor readableANTONIO; 06-janv.-05


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Construction material RequirementConstruction material Requirement



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3.4.1. Construction material requirement: 3.4.1. Construction material requirement: Construction Plant Materials Requirements Construction Plant Materials Requirements and pipelineand pipeline

The next table list materials requirements used for the plant inThe next table list materials requirements used for the plant in this study. A sensitivity this study. A sensitivity analysis was performed how changing these numbers would affect tanalysis was performed how changing these numbers would affect the results.he results.

37.12Iron

25.06Aluminum

3036.4Steel

9504.6Concrete

Amount required(Mg)

Material

Hydrogen Plant Material Requirement (Base Case)Hydrogen Plant Material Requirement (Base Case)


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To move the natural gas from the oil or gas wells to the hydrogeTo move the natural gas from the oil or gas wells to the hydrogen plant, we use n plant, we use pipelines. Because the main pipeline is shared by many users, onpipelines. Because the main pipeline is shared by many users, only a portion of the ly a portion of the material requirement was allocated for the natural gas combinedmaterial requirement was allocated for the natural gas combined--cycle plant. For this cycle plant. For this analysis, the total length of pipeline transport for the naturalanalysis, the total length of pipeline transport for the natural gas combinedgas combined--cycle plant cycle plant is assumed to be 425 km, it was sized so that the total pressureis assumed to be 425 km, it was sized so that the total pressure drop in the pipe is of drop in the pipe is of 0.05 psi/100 feet (0.001 MPa/100 meters). The pipe has a diamete0.05 psi/100 feet (0.001 MPa/100 meters). The pipe has a diameter of 31 inches r of 31 inches assuming a wall thickness of 1 inch. The steel used for the pipassuming a wall thickness of 1 inch. The steel used for the pipe construction has a e construction has a density of 7700 kg/m3. density of 7700 kg/m3.


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3.4.1. Air Emissions due to materials3.4.1. Air Emissions due to materials’’ constructionconstruction

0.504Particulate

15.08NMHCs

50.3CH4

6.48SO2

6.86NO2

0.0150N2O

5.46CO

1614.3CO2

1.4Benzene(C6H6)

g of emission/Kg of H2 produced

Air emission

The construction of materials The construction of materials requirements also produce a lot of air requirements also produce a lot of air emissions. Because of lack of data, we emissions. Because of lack of data, we will suppose that those constructions emit will suppose that those constructions emit 2.8652 ton of particulate/hectare of the 2.8652 ton of particulate/hectare of the mill/month of activity. mill/month of activity.

You can suppose that You can suppose that NMHCsNMHCs = 50% mass. benzene + 50% mass. Toluene.= 50% mass. benzene + 50% mass. Toluene.

Air emissions due to the plant constructionAir emissions due to the plant construction

A8

A8 Air emissions are not "construction material", better to say emission due to constructing the materials, or similarANTONIO; 06-janv.-05


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Construction material RequirementConstruction material RequirementNatural gas composition and lostNatural gas composition and lost



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3.4.2. Natural gas composition and loss 3.4.2. Natural gas composition and loss

While natural gas is generally though of as methane, about 5While natural gas is generally though of as methane, about 5--25% of the volume is 25% of the volume is comprised of ethane, propane, butane, hydrogen sulfide, and comprised of ethane, propane, butane, hydrogen sulfide, and inertsinerts (nitrogen, CO2 and (nitrogen, CO2 and helium). The relative amounts of these components can vary greathelium). The relative amounts of these components can vary greatly depending on the ly depending on the location of the wellhead. The next table gives the composition olocation of the wellhead. The next table gives the composition of the natural gas f the natural gas feedstock use in this analysis, as well as typical pipeline and feedstock use in this analysis, as well as typical pipeline and wellhead compositions. wellhead compositions. The composition used in this study (first column) assumes that tThe composition used in this study (first column) assumes that the natural gas has he natural gas has undergo a pretreatment before entering the desulphurization reacundergo a pretreatment before entering the desulphurization reactor. The natural gas tor. The natural gas feedstock contains up to 7 ppmv total sulfur, max. 5 ppmv in thefeedstock contains up to 7 ppmv total sulfur, max. 5 ppmv in the form of hydrogen form of hydrogen sulphide (H2S) and max. 2 ppmv organic sulfur as mercaptane. sulphide (H2S) and max. 2 ppmv organic sulfur as mercaptane.

A9

A9 what is "lost" here?, maybe loss?ANTONIO; 06-janv.-05


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Natural Gas CompositionNatural Gas Composition

----00.03N- +(C6)

----02.91Hydrogen (H2)

----00.03N-pentane

100.04Pentanes (C5+)

200.17N-butane (C4H10)

100.11Iso-butane (C4H10)

1000.78Carbon Dioxide (CO2)

1501.00Nitrogen (N2)

1011.15Propane (C3H8)

15110.19Ethane (C2H6)

997583.59Methane (CH4)

High valueLow valueMol % (dry)Component

Typical range of wellhead components (mol%)

Natural gas feedstock used in analysis


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In extracting, process, transmitting, storing and distributing nIn extracting, process, transmitting, storing and distributing natural gas, some is lost to atural gas, some is lost to the atmosphere. Over the past two decades, the natural gas industhe atmosphere. Over the past two decades, the natural gas industry and others have try and others have tried to better quantify the losses. There is a general consensutried to better quantify the losses. There is a general consensus that fugitive emissions s that fugitive emissions are the largest source, accounting for about 38% of the total, aare the largest source, accounting for about 38% of the total, and that nearly 90% of nd that nearly 90% of the fugitive emissions are a result of leaking compressor componthe fugitive emissions are a result of leaking compressor components. The second ents. The second largest source of methane emissions comes from pneumatic controllargest source of methane emissions comes from pneumatic control devices, devices, accounting for approximately 20% of the total losses. accounting for approximately 20% of the total losses.

The majority of the pneumatic losses happen during the extractioThe majority of the pneumatic losses happen during the extraction step. Engine n step. Engine exhaust is the third largest source of methane emissions due to exhaust is the third largest source of methane emissions due to incomplete combustion incomplete combustion in reciprocating engines and turbines used in moving the naturalin reciprocating engines and turbines used in moving the natural gas through the gas through the pipeline. These three sources make up nearly 75 % of the overallpipeline. These three sources make up nearly 75 % of the overall estimated methane estimated methane emissions. The remaining 25% come from sources such as dehydratoemissions. The remaining 25% come from sources such as dehydrators, purging of rs, purging of transmissions/storage equipment, and meter and pressure regulatitransmissions/storage equipment, and meter and pressure regulating stations in ng stations in distribution lines. distribution lines.


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1.1. Description of the context: Hydrogen production via natural gas Description of the context: Hydrogen production via natural gas steam steam reformingreforming

2.2. Problem statementProblem statement3.3. Statement of the intent Statement of the intent


Construction material RequirementConstruction material RequirementNatural gas composition and lostNatural gas composition and lostProduction and distribution of electricityProduction and distribution of electricity



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3.4.3. production and distribution of electricity 3.4.3. production and distribution of electricity

Electricity is purchased from the grid to operate the pumps andElectricity is purchased from the grid to operate the pumps and compressors. The compressors. The production was assumed to be the generation mix of coal, ligniteproduction was assumed to be the generation mix of coal, lignite (hard coal), oil and (hard coal), oil and fuel/natural gas. The process consume approx. 129,104 fuel/natural gas. The process consume approx. 129,104 MjMj/day. Each fuel provide /day. Each fuel provide respectively 3%, 2%, 72% and 23% of the total energy needed by trespectively 3%, 2%, 72% and 23% of the total energy needed by the process. The he process. The stressors associated with this mix should also determined in a cstressors associated with this mix should also determined in a cradleradle--toto--grave manner. grave manner. The table below presents the quantity The table below presents the quantity (in(in kg) of air emissions for each fossil fuel used kg) of air emissions for each fossil fuel used for electricity production. Those data relate to a functional unfor electricity production. Those data relate to a functional unit of 1 it of 1 TjTj net electricity net electricity delivered from the power plant.delivered from the power plant.

1.8

257.66

3623.53

12.6

45.1

370979

Lignite

5.531.51.79N2O

96.8716.13321.59Particulates

2359.458.291062.07SO2

488408.44451.7NOx

75.1581.9756.6CO

229380245831275833CO2

OilFuel gasCoal

A11

A11 in kgANTONIO; 06-janv.-05


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Construction material RequirementConstruction material RequirementNatural gas composition and lostNatural gas composition and lostProduction and distribution of electricityProduction and distribution of electricityHH22 Production plantProduction plant



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3.4.4. H3.4.4. H22 Production plant Production plant Hydrogenation and DesulphurizationHydrogenation and Desulphurization

As the reformer catalyst is sensitive to poisoning from sulfur, As the reformer catalyst is sensitive to poisoning from sulfur, sulfur in the natural sulfur in the natural gasisgasisprocessed in a Hydrogenation Reactor. Sulfur is processed in a Hydrogenation Reactor. Sulfur is totalytotaly converted to hydrogen sulfide in converted to hydrogen sulfide in this Hydrogenation reactor and will be absorbed on the zinc oxidthis Hydrogenation reactor and will be absorbed on the zinc oxide by conversion of e by conversion of ZnOZnO to to ZnSZnS in the desulphurization reactor. Natural gas leaving the reactoin the desulphurization reactor. Natural gas leaving the reactor will have a r will have a residual sulfur content of less than 0.2 ppmv.residual sulfur content of less than 0.2 ppmv.The total adsorption capacity of the desulphurization catalyst, The total adsorption capacity of the desulphurization catalyst, based on total 7 ppmv based on total 7 ppmv sulfur in the feedstock will be for minimum 2 years of uninterrsulfur in the feedstock will be for minimum 2 years of uninterrupted operation.upted operation.A small amount of hydrogen, which is recycled from the product sA small amount of hydrogen, which is recycled from the product stream, is used in the tream, is used in the Hydrogenation step to adjust the Hydrogenation step to adjust the pressurepressure in the reactor. The table below gives the in the reactor. The table below gives the caractheristicscaractheristics of the inflow of the hydrogenation reactor.of the inflow of the hydrogenation reactor.

The flow in

Kmol/hKg/h

2857Hydrogen (H2)

96217222Natural gas feedstock

Inflows to the hydrogenation reactorInflows to the hydrogenation reactor

A10

A10 pressureANTONIO; 06-janv.-05


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3.4.4. H3.4.4. H22 Production plant Production plant Steam reformingSteam reforming

In the steam reforming, the mixture of In the steam reforming, the mixture of desulphurizeddesulphurized natural gas and process steam natural gas and process steam (3358 (3358 kmol/hkmol/h at 2.6 at 2.6 MPaMPa (380 (380 psipsi)) is reformed under application or external heat. )) is reformed under application or external heat. The principle chemical reactions taking place in the steam reforThe principle chemical reactions taking place in the steam reformer are as follows:mer are as follows:

Steam reformingSteam reforming

heatHmnnCOOnHHC mn −++↔+ 22 )2/(

WaterWater--gas Shift reaction (which is highly exothermic)gas Shift reaction (which is highly exothermic)

heatHCOOHCO ++↔+ 222

The effluent contains besides the products CO2 and residual CH4 The effluent contains besides the products CO2 and residual CH4 and H2O. The and H2O. The reformed gas leaves the SR at 810reformed gas leaves the SR at 810ººC and approx. 25 kg/cm2 abs.. All reactions take C and approx. 25 kg/cm2 abs.. All reactions take place simultaneously at about 560place simultaneously at about 560ººC. However, the reaction as a whole is C. However, the reaction as a whole is endothermic. Those reactions take place over a nickelendothermic. Those reactions take place over a nickel--based catalyst.based catalyst.

The waste heat contained in the furnace flue gas is utilized forThe waste heat contained in the furnace flue gas is utilized for superheating of the superheating of the reformer feedstock, generating of medium pressure steam, superhereformer feedstock, generating of medium pressure steam, superheating of the ating of the medium pressure steam and preheating of the combustion air. Thosmedium pressure steam and preheating of the combustion air. Those gases leave the e gases leave the reformer at approx. 1000reformer at approx. 1000ººC.C.


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38.07H2O

0N-C6

43.73H2

7.08CO

0N-C5

0i-C5

0N-C4

0i-C4

0C3

0C2

4.75C1

0.16N2

6.2CO2

% mol.Components

The reformed gas compositionThe reformed gas composition


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The combustion air given is based on 5% excess air and enters thThe combustion air given is based on 5% excess air and enters the burner at 380e burner at 380ººC C and approx. 1.2 kg/cm2, at a rate of 123488 kg/h. It is composeand approx. 1.2 kg/cm2, at a rate of 123488 kg/h. It is composed of 20.4% mol. O2, d of 20.4% mol. O2, 76.77% mol. N2 and 2.83% of H2O.76.77% mol. N2 and 2.83% of H2O.Waste heat is recovered from the flue gas as well as from the reWaste heat is recovered from the flue gas as well as from the reformed gas to formed gas to preheat and superheat process streams and for steam production. preheat and superheat process streams and for steam production.

The natural gas utilized as fuel for the burner contains 5 ppmv The natural gas utilized as fuel for the burner contains 5 ppmv of H2S and 2 ppmv of of H2S and 2 ppmv of mercaptane and has the following composition and characteristicmercaptane and has the following composition and characteristics:s:

2Pression (kg/cm2)

20Temperature (ºC)

26.4Flow in kmol/h

18.38Molar mass (kg/mol)


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0.04N-C6

0.04N-C5

0.04i-C5

0.17N-C4

0.11i-C4

1.18C3

10.5C2

86.1C1

1.02N2

0.8CO2

% mol.ComponentsThe table below The table below presentspresents the the composition of the flue gas at the composition of the flue gas at the outlet of the burners.outlet of the burners.

19.38H2O

60.28N2

1.05O2

19.28CO2

% mol.Components

Molar composition of Molar composition of ofof the natural gas used in the burnerthe natural gas used in the burner


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3.4.4. H3.4.4. H22 Production plant Production plant High Temperature Shift (HTS)High Temperature Shift (HTS)

The carbon monoxide, which is produced in the steam reformer, isThe carbon monoxide, which is produced in the steam reformer, is converted by converted by means of water vapor on a catalyst in a HTS reactor to hydrogen means of water vapor on a catalyst in a HTS reactor to hydrogen and carbon dioxide, and carbon dioxide, according to the following reaction:according to the following reaction:

This reaction is highly exothermic, which leads to temperature rThis reaction is highly exothermic, which leads to temperature rise of about 50ise of about 50ººC. The C. The COCO--content at the outlet of the Shift reactor is less than 2 molcontent at the outlet of the Shift reactor is less than 2 mol--%. Subsequently the %. Subsequently the shifted gas is cooled down in different exchangers to approx. 36shifted gas is cooled down in different exchangers to approx. 36ººC. Process C. Process condensate is separated in multiple liquidcondensate is separated in multiple liquid--gas separators. The gas is then routed to gas separators. The gas is then routed to the PSA Unit.the PSA Unit.

heatHCOOHCO ++↔+ 222


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3.4.4. H3.4.4. H22 Production plant Production plant SeparatorsSeparators

The outflow gas from the HTS passes by different exchangers and The outflow gas from the HTS passes by different exchangers and liquidliquid--gas gas separators. At the outlet of the last separator, we obtain two fseparators. At the outlet of the last separator, we obtain two flows. On flow of 481 lows. On flow of 481 kg/h of liquid water at 35kg/h of liquid water at 35ººC and a gaseous flow principally composed of hydrogen C and a gaseous flow principally composed of hydrogen (H2) and carbon dioxide (CO2) at a rate of 43186 kg/h (3945 (H2) and carbon dioxide (CO2) at a rate of 43186 kg/h (3945 kmol/hkmol/h). The table ). The table bellow gives the molar composition of this gaseous flow:bellow gives the molar composition of this gaseous flow:

7.07CH4

0.24N2

0.27H2O

72.7H2

2.8CO

16.92CO2

% mol.Component

Molar composition of the gaseous outflow of the last Molar composition of the gaseous outflow of the last separator before the PSA unitseparator before the PSA unit


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3.4.4. H3.4.4. H22 Production plant Production plant Pressure Swing absorption (PSA)Pressure Swing absorption (PSA)

For final purification a Pressure Swing Adsorption process is usFor final purification a Pressure Swing Adsorption process is used. The reminder of ed. The reminder of undesired components are removed from the bulk of hydrogen by meundesired components are removed from the bulk of hydrogen by means of ans of adsorption on molecular sieves using a PSA. The purification of adsorption on molecular sieves using a PSA. The purification of hydrogen is based on hydrogen is based on selective adsorption of gas components such as CH4, CO, CO2, N2 selective adsorption of gas components such as CH4, CO, CO2, N2 and H2O. and H2O. Hydrogen does not absorb and leaves the PSA unit as a product gaHydrogen does not absorb and leaves the PSA unit as a product gas with high purity. s with high purity. Subsequently the pure hydrogen product is compressed and a smalSubsequently the pure hydrogen product is compressed and a small amount is l amount is recycled to upstream of the Hydrogenation Reactor. recycled to upstream of the Hydrogenation Reactor.

The adsorbed gases in the PSA are released and routed as offThe adsorbed gases in the PSA are released and routed as off--gases to the off gas gases to the off gas which ensures a stable and constant supply of fuel gas to the buwhich ensures a stable and constant supply of fuel gas to the burners of the reformer.rners of the reformer.

The Hydrogen (H2) obtained from the PSA has a 99% molar purity. The Hydrogen (H2) obtained from the PSA has a 99% molar purity. It leaves the PSA It leaves the PSA Unit at 40Unit at 40ººC at 5149 kg/h (2525 C at 5149 kg/h (2525 kmol/hkmol/h).).


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3.4.4. H3.4.4. H22 Production plant Production plant Steam Generation SystemSteam Generation System

Waste heat from the process is utilized for steam generation. AsWaste heat from the process is utilized for steam generation. As the main source of the main source of energy, the sensible heat of the reformed gas downstream Steam Renergy, the sensible heat of the reformed gas downstream Steam Reformer is used eformer is used for steam production in Reformed Gas Waste Heat Boiler. An othefor steam production in Reformed Gas Waste Heat Boiler. An other source of heat for r source of heat for steam generation is the waste heat of the flue gas leaving the ssteam generation is the waste heat of the flue gas leaving the steam reformer. Here team reformer. Here additional steam is produced in Flue Gas Waste Heat Boiler.additional steam is produced in Flue Gas Waste Heat Boiler.


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3.4.4. H3.4.4. H22 Production plant Production plant Shut downShut down

TheThe processprocess isis shutedshuted down for 24 down for 24 hourshours everyevery 2 2 yearsyears to change to change thethe catalystscatalysts. . DuringDuring startstart--up up ofof thethe processprocess or PSA Unit or PSA Unit failurefailure, , wewe use a use a burnersburners’’ fuel (for fuel (for thethe SR) SR) composedcomposed in in majoritymajority ofof naturalnatural gasgas (12.88 (12.88 thethe mole rate mole rate ofof thethe naturalnatural gasgas usedused in in normal normal operationoperation case) case) completedcompleted withwith RaffineryRaffinery fuel. fuel. TheThe mole ratio mole ratio ofof thosesthoses twotwofuels fuels isis 8.5.8.5. A12

A12 spelling, what is thosesANTONIO; 06-janv.-05


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4.4. Report structureReport structure



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4.1. Questions for discussion4.1. Questions for discussion

11-- Quantify the environmental loads Quantify the environmental loads -- resource use and pollutant air emissions resource use and pollutant air emissions -- of of the system.the system.

22-- Make the results more environmentally relevant by translating tMake the results more environmentally relevant by translating the emissions using he emissions using environmental themes method. Identify and evaluate the environmeenvironmental themes method. Identify and evaluate the environmental impacts of ntal impacts of the process by making an impact assessment by calculating the tothe process by making an impact assessment by calculating the total impact. The tal impact. The index list is in the Index towards the end of the problem.index list is in the Index towards the end of the problem.


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4.1. Questions for discussion4.1. Questions for discussion

33-- Make a sensitivity study and identify the most important parameMake a sensitivity study and identify the most important parameters toward their ters toward their influence on the results of this study.influence on the results of this study.

44-- Examine the net emission of Examine the net emission of greenhouse gasesgreenhouse gases, as well as the major environmental , as well as the major environmental consequences.consequences.

55-- Substitutions scenarios: What possible improvements on the sysSubstitutions scenarios: What possible improvements on the system could we do ?tem could we do ?

77-- Make a costMake a cost--benefit Analysis, typically involves an economic ROI study.benefit Analysis, typically involves an economic ROI study.

88-- Since Risk is another matter not dealt with in LCA, we wonSince Risk is another matter not dealt with in LCA, we won’’t t askask you about it but you about it but you should write a short paragraph about the Ecological Risk Assyou should write a short paragraph about the Ecological Risk Assessment (ERA) related essment (ERA) related to this process.to this process.


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4.2. Suggestion for Report Table of Contents4.2. Suggestion for Report Table of Contents

1.1. ExecutiveExecutive summurysummury2.2. IntroductionIntroduction3.3. ObjectivesObjectives4.4. SummurySummury ofof resultsresults5.5. SensitivitySensitivity AnalysisAnalysis6.6. ImpactImpact AssessmentAssessment7.7. ImpovementImpovement OpportunitiesOpportunities8.8. ConclusionsConclusions


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4.4. Report structureReport structure5.5. RecommendationsRecommendations



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5.5. RecommendationsRecommendations

1.1. When reporting the final results of your work it is important toWhen reporting the final results of your work it is important tothoroughly describe the methodology used in this analysis. The rthoroughly describe the methodology used in this analysis. The report eport should explicitly define the system analyzed and the boundaries should explicitly define the system analyzed and the boundaries that that were set.were set.

2.2. All assumptions or decisions made in performing the work should All assumptions or decisions made in performing the work should be be clearly explained and reported along side the final results of tclearly explained and reported along side the final results of this project.his project.

3.3. The results should not be oversimplified solely for the purposesThe results should not be oversimplified solely for the purposes of of presentation.presentation.

4.4. All the environnemental data needed to do this work are given toAll the environnemental data needed to do this work are given towards wards the end of the problem (in the Index).the end of the problem (in the Index).

5.5. You should respect the international standards for LCA (ISO 1404You should respect the international standards for LCA (ISO 140400--14043) when performing the different steps of the 14043) when performing the different steps of the analyzeanalyze..


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End of Tier IIIEnd of Tier III

•• This is the end of Module 14. Please submit your report to yourThis is the end of Module 14. Please submit your report to your professor for professor for grading. grading.

•• We are always interested in suggestions on how to improve the coWe are always interested in suggestions on how to improve the course. You may urse. You may contact us atcontact us at www.namppimodule.orgwww.namppimodule.org


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INDEX


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To meet the needs of this study, categorization and lessTo meet the needs of this study, categorization and less--isis--better approaches have been better approaches have been taken. The next table summarizes the stressors categories and mataken. The next table summarizes the stressors categories and main stressors from the in stressors from the natural gas steam reforming, hydrogen production system. natural gas steam reforming, hydrogen production system.

Impact Impact CategoriesCategories

4.81 x 10-4 kg Sbeq/MjFossil energy

0.00671 kg Sbeq/kgSoft coal

0.0134 kg Sbeq/kgHard coal

0.0187 kg Sbeq/m3.Natural gas

Static reserve life (years)Substance

1. Depletion of 1. Depletion of abioticabiotic resourcesresources

Depletion equivalents for Depletion equivalents for abioticabiotic resources, resources, expressed relative to antimony (expressed relative to antimony (SbSb) and based ) and based

on ultimate reserves.on ultimate reserves.


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2. Global warming2. Global warming

320NO2

310N2O

25CH4

1CO2

GWP 100 years(kg CO2 eqv/kg)

Trace gas

3. Acidification3. Acidification

0.7NOx

1SO2

AP (g SO2 eqv/g)Substance

Global warning potentials for 100 Global warning potentials for 100 years expressed in relative to CO2years expressed in relative to CO2

Generic acidification equivalents expressed relative to SO2 (CML/NOH 1992; in CML 2002)


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4. Photochemical ozone creation potential (contribution to smog)4. Photochemical ozone creation potential (contribution to smog)

0.637Toluene

0.218Benzene

0.495N-C6

0.395N-pentane

0.352N-butane

0.176Propane

0.123Ethane

0.006Methane

0.028NO2

0.027CO

High NOx POCPs(kg ethylene/kg)

Substance

Photochemical ozone creation potentials (POCPs) for high NOx background concentrations expressed

relative to ethylene (CML 2002)


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5. Human toxicity5. Human toxicityHuman toxicity Human toxicity potentielspotentiels, , HTPinfHTPinf, for infinite horizon and global scale. The indicators , for infinite horizon and global scale. The indicators are expressed relative to 1,4are expressed relative to 1,4--dichlorobenzenedichlorobenzene

6. 6. EutrophicationEutrophicationGeneric Generic eutrophicationeutrophication equivalents for emissions to air, water and soil. Indicators arequivalents for emissions to air, water and soil. Indicators are e expressed relative to PO3expressed relative to PO3--4 (CML/NOH 1992; CML 2002).4 (CML/NOH 1992; CML 2002).

0.33Toluene

1900Benzene

0.096SO2

1.2NO2

HTP for emissions to airSubstance

0.33NH4+

0.42N

0.35NH3

3.06P

0.97H3 PO4

1PO3-4

(g PO3-4 /g)Substance


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Impacts Associated with Stressor CategoriesImpacts Associated with Stressor Categories

L, RH, E

Catalysts, coal ash (indirectly), flue gas clean up waste (indirectly)

Solid waste

R, GEFossil fuels,

water, minerals and ores

Resource depletion

LH, ENMHCs, benzeneOther stressors with toxic effects

LESO2, H2S, H2OContributors to corrosion

L, RH, ESO2, NOx, CO2Acidification precursors

L, RH, ENOx, VOCsPhotoquemicalContributors to smog

L, RH, EParticulates

R, GH, E

CO2, CH4, N2O, CO and NOx (indirectly), water vapor

GreenhouseGasesClimate change

R, GH, ENOOzone depletion compounds

MinorMajor

Area impacted L=local (country) R=regional (state)

G=global

Major Impact category

H=human health E=ecological health

StressorsStressors categories

L, RH, E

Catalysts, coal ash (indirectly), flue gas clean up waste (indirectly)

Solid waste

R, GEFossil fuels,

water, minerals and ores

Resource depletion

LH, ENMHCs, benzeneOther stressors with toxic effects

LESO2, H2S, H2OContributors to corrosion

L, RH, ESO2, NOx, CO2Acidification precursors

L, RH, ENOx, VOCsPhotoquemicalContributors to smog

L, RH, EParticulates

R, GH, E

CO2, CH4, N2O, CO and NOx (indirectly), water vapor

GreenhouseGasesClimate change

R, GH, ENOOzone depletion compounds

MinorMajor

Area impacted L=local (country) R=regional (state)

G=global

Major Impact category

H=human health E=ecological health

StressorsStressors categories


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Economic dataEconomic data

5.198 5.198 US/LUS/L

36.536.5An iron chrome and copper An iron chrome and copper promoted iron chrome based promoted iron chrome based catalyst.catalyst.

CopperCopper OxideOxide--ZincZinc OxideOxide on on Alumina Alumina

HTSHTS

----------

3.237 3.237 US/LUS/L

3.5 3.5 US/US/lblb

PricePrice

7.27.2------------------------------------------------------------------------------------HydrogenationHydrogenationreactorreactor

23.623.6A nickel based catalyst on A nickel based catalyst on alpha alumina carrier or alpha alumina carrier or calcium calcium aluminatealuminate compound compound in the form of rings/high in the form of rings/high geometric surface rings.geometric surface rings.

Nickel Nickel BasedBasedSRSR

16.516.5Zinc Oxide based catalyst Zinc Oxide based catalyst having specific physical and having specific physical and textural properties blended textural properties blended with suitable binders in the with suitable binders in the form of pelletsform of pellets

Zinc Zinc OxideOxide DesulphurisationDesulphurisationCatalystCatalyst ((ZnODsZnODs))

DesulphurisationDesulphurisationreactorreactor

QuantityQuantity(m(m33))

DescriptionDescriptionTheThe catalystcatalystTheThe reactorreactor

CatalystsCatalysts

Due to lack of data, we suppose that all these catalysts have thDue to lack of data, we suppose that all these catalysts have the same density than e same density than water.water.


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11FeedFeed preheaterpreheaterShellShell-- tube HEtube HE

11For fuel For fuel gasgasDrumDrum

11ShiftedShifted gasgas separatorseparatorDrumDrum

11ShiftedShifted gasgas separatorseparatorDrumDrum

11GasGas separatorseparatorDrumDrum

11For For flareflare gasgasDrumDrum

11Tank Tank andand deaeratordeaeratorDrumDrum

11SteamSteam condensatecondensateDrumDrum

22H2 H2 compressorcompressor, , ReciprocatingReciprocating, , IsentropicIsentropicCompressorCompressor

22CentrifugalCentrifugal; ; EmotorEmotor; ; IsentropicIsentropic; Flue ; Flue gasgas FanFanCompressorCompressor

33CentrifugalCentrifugal; ; EmotorEmotor; ; IsentropicIsentropic; Combustion Air Fan; Combustion Air FanCompressorCompressor

11For For waterwaterVesselVessel

QuantityDescription/UtilityEquipment

EquipmentEquipment


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TOTALTOTAL

22Turbine for Turbine for FluegasFluegas Fan; Fan; backback--pressurepressure turbineturbineSteamturbineSteamturbine

2525

11For BFW For BFW pumppump; ; backback--pressurepressure turbineturbineSteamturbineSteamturbine

11HTSHTSReactorReactor

11DesulphurizationDesulphurization, jacket, jacketReactorReactor

11HydrogenationHydrogenation withwith jacketjacketReactorReactor

22FlareFlare condensatecondensate; ; DrumDrum pumppumpPumpsPumps

22CentrifugalCentrifugal; team turbine; team turbinePumpsPumps

11AtAt thethe feedfeedStaticStatic MixerMixer

11ReformedReformed gasgas air air coolercoolerAir Air CoolerCooler

11Blow down Blow down coolercoolerPlate HEPlate HE

11ReformedReformed gasgas final final coolercoolerShellShell-- tube HEtube HE

11BFWBFW--PreheaterPreheaterShellShell-- tube HEtube HE

Also consider that you need 3 feeds for the alimentation and the effluents and that you have 2 purges.Consider also that we use a Straightline depreciation during 10 years with a resale price of 0$.


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HH22 priceprice

Gray and Tomlinson (2000) Gray and Tomlinson (2000) proposed equations to calculate the hydrogen costs based proposed equations to calculate the hydrogen costs based on the prices of fuels in the worldon the prices of fuels in the world--wide market, in these equations it is assumed that wide market, in these equations it is assumed that the value of hydrogen is equal to the cost of producing it from the value of hydrogen is equal to the cost of producing it from reformation. Based on reformation. Based on this the cost of sale of hydrogen is given by:this the cost of sale of hydrogen is given by:

CSH = 0.45CSH = 0.45••CGN + 0.76 CGN + 0.76 WhereWhere::

CSH = CSH = CostCost ofof HydrogenHydrogen DutyDuty ($/MPCSD)($/MPCSD)CGN = CGN = CostCost ofof Natural Gas ($/Natural Gas ($/MMBtuMMBtu))

GrayGray y y TomlinsonTomlinson (2000)(2000) also established a simple equation to estimate the cost of the also established a simple equation to estimate the cost of the natural gas in function of the price of petroleum in the world, natural gas in function of the price of petroleum in the world, which is:which is:

CGN = 0.13CGN = 0.13••PPM PPM WhereWhere::

PPM = PPM = PricePrice ofof thethe PetrolPetrol in in thethe World ($/BBL)World ($/BBL)

Most of the hydrogen produced at the present time is consumed inMost of the hydrogen produced at the present time is consumed in its site of its site of production. When it is sold in the market, to its production cosproduction. When it is sold in the market, to its production cost is added the cost of t is added the cost of liquefying it and of transporting it.liquefying it and of transporting it.

A13

A13 why those equation numbers?, same in next pagesANTONIO; 06-janv.-05


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Electricity costElectricity cost

In order to calculate the cost of the electricity used to producIn order to calculate the cost of the electricity used to produce hydrogen, Gray and e hydrogen, Gray and Tomlinson (2000) assumed that the value of the electricity is deTomlinson (2000) assumed that the value of the electricity is determined by the cost of termined by the cost of producing it with a advanced plant of combined cycle of natural producing it with a advanced plant of combined cycle of natural gas. It was assumed gas. It was assumed that the cost of capital of this type of plants is of $494/kw anthat the cost of capital of this type of plants is of $494/kw and an amount of specified d an amount of specified energy of 6.396 BTU/KW. Based on these estimations the sale pricenergy of 6.396 BTU/KW. Based on these estimations the sale price required of the e required of the electricity it is given by the following equation:electricity it is given by the following equation:

CEPH = 0.0064CEPH = 0.0064••CGN + 0.0116CGN + 0.0116WhereWhere: :

CEPH = CEPH = CostCost ofof electricityelectricity forfor produce produce hydrogenhydrogen ($/($/KWh)KWh)

...the end....the end.


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Complementary Complementary informationinformation

Hydrogen EnergyHydrogen Energy

Hydrogen is the simplest element. ItHydrogen is the simplest element. It’’s also the most plentiful element in the universe. s also the most plentiful element in the universe. Despite its simplicity and abundance, hydrogen doesnDespite its simplicity and abundance, hydrogen doesn’’t occur naturally as a gas on the t occur naturally as a gas on the EarthEarth-- itit’’s always combined with other elements.s always combined with other elements.

Hydrogen is produced from sources such as natural gas, coal, gasHydrogen is produced from sources such as natural gas, coal, gasoline, methanol or oline, methanol or biomass through application of heat; from bacteria or algae Throbiomass through application of heat; from bacteria or algae Through photosynthesis; or ugh photosynthesis; or by using electricity or sunlight into hydrogen and oxygen.by using electricity or sunlight into hydrogen and oxygen.

Hydrogen is high in energy, yet an engine that burns pure hydroHydrogen is high in energy, yet an engine that burns pure hydrogen produces almost gen produces almost no pollution. Hydrogen fuel cells power the shuttleno pollution. Hydrogen fuel cells power the shuttle’’s electrical system, producing a clean s electrical system, producing a clean byproductbyproduct--pure water, which the crew drinks.pure water, which the crew drinks.


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Hydrogen EnergyHydrogen Energy

A fuel cell combines hydrogen and oxygen to produce electricity,A fuel cell combines hydrogen and oxygen to produce electricity, heat and water. Fuel heat and water. Fuel cells are often compared to batteries. Both convert the energy pcells are often compared to batteries. Both convert the energy produced by a chemical roduced by a chemical reaction into usable electric power. However, the fuel cell willreaction into usable electric power. However, the fuel cell will produce electricity as long produce electricity as long as fuel (hydrogen) is supplied, never losing its charge.as fuel (hydrogen) is supplied, never losing its charge.

In the future, hydrogen could also join electricity as an importIn the future, hydrogen could also join electricity as an important energy carrier.ant energy carrier.

Some experts think that hydrogen will from the basic energy infrSome experts think that hydrogen will from the basic energy infrastructure that will astructure that will power future power future sociesocie replacing todayreplacing today’’s natural gas, oil, coal and electricity infrastructures. s natural gas, oil, coal and electricity infrastructures. They see a new hydrogen They see a new hydrogen econoreconor our current energy economies, although that vision our current energy economies, although that vision probably wonprobably won’’t happen until far in the future.t happen until far in the future.


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Steam Reforming of Natural GasSteam Reforming of Natural Gas

Steam reforming of natural gas is currently the least expensive Steam reforming of natural gas is currently the least expensive method of producing method of producing hydrogen, and used for about half of the worldhydrogen, and used for about half of the world’’s production of hydrogen. Steam, at a s production of hydrogen. Steam, at a temperature of 700 temperature of 700 –– 1100 1100 ooCC is mixed with methane gas is a reactor with a catalyst at is mixed with methane gas is a reactor with a catalyst at 3 3 –– 25 bar pressure.25 bar pressure.

Thirty percent more natural gas in required for this process, buThirty percent more natural gas in required for this process, but new process are t new process are constantly being developed to increase the rate of production. Iconstantly being developed to increase the rate of production. It is possible to increase t is possible to increase the efficiency to over 85% with a economic profit at higher therthe efficiency to over 85% with a economic profit at higher thermal integration.mal integration.

A large steam reformer which produces 100 000 tons of hydrogen aA large steam reformer which produces 100 000 tons of hydrogen a year can supply year can supply roughly one million fuel cell cars with an annual average drivinroughly one million fuel cell cars with an annual average driving range of 16 000 km.g range of 16 000 km.

There are two types of steam reformers for smallThere are two types of steam reformers for small--scale hydrogen production: scale hydrogen production: Conventional reducedConventional reduced--scale reformers and specially designed reformers for fuel cellsscale reformers and specially designed reformers for fuel cells. . The latter operates under lower pressure and temperatures than cThe latter operates under lower pressure and temperatures than conventional reformers onventional reformers and is more compact.and is more compact.


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Steam Reforming of Natural GasSteam Reforming of Natural Gas

The formula for this process is:The formula for this process is:

CH4 + H2O CH4 + H2O --> CO + 3 H2> CO + 3 H2

It is usually followed by the shift reaction:It is usually followed by the shift reaction:

CO + H2O CO + H2O --> CO2 + H2> CO2 + H21 mol methane 1 mol methane --> 4 mol hydrogen> 4 mol hydrogen

The percentage of hydrogen to water is 50%The percentage of hydrogen to water is 50%

In steam reforming of natural gas, 7.05 kg CO2 are produced per In steam reforming of natural gas, 7.05 kg CO2 are produced per kg hydrogen.kg hydrogen.


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Greenhouse gasesGreenhouse gases

Some greenhouse gases occur naturally in the atmosphere, while oSome greenhouse gases occur naturally in the atmosphere, while others result from thers result from human activities. Naturally occurring greenhouse gases include whuman activities. Naturally occurring greenhouse gases include water vapor , carbon ater vapor , carbon dioxide, methane, nitrous oxide and ozone. Certain human activitdioxide, methane, nitrous oxide and ozone. Certain human activities, however, add to ies, however, add to the levels of most of these naturally occurring gases:the levels of most of these naturally occurring gases:

Carbon dioxideCarbon dioxide is released to the atmosphere when solid waste, fossil fuels (ois released to the atmosphere when solid waste, fossil fuels (oil, natural il, natural gas, and coal), and wood and wood products are burned.gas, and coal), and wood and wood products are burned.

MethaneMethane is emitted during the production and transportation of coal, nais emitted during the production and transportation of coal, natural gas and oil. tural gas and oil. Methane emissions also result from the decomposition of organic Methane emissions also result from the decomposition of organic wastes in municipal wastes in municipal solid waste landfills and the rising of livestock.solid waste landfills and the rising of livestock.

Nitrous oxideNitrous oxide is emitted during agricultural and industrial activities, as weis emitted during agricultural and industrial activities, as well as during ll as during combustion of solid waste and fossil fuels.combustion of solid waste and fossil fuels.


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Greenhouse gasesGreenhouse gases

Very powerful greenhouse gases that are not naturally occurring Very powerful greenhouse gases that are not naturally occurring include include hydrofluorocarbonshydrofluorocarbons ((HFCsHFCs), ), perfluorocarbonsperfluorocarbons ((PFCsPFCs), and sulfur hexafluoride (SF6), ), and sulfur hexafluoride (SF6), which are generated in a variety of industrial processes.which are generated in a variety of industrial processes.

Each greenhouse gas differs in its ability to absorb heat in theEach greenhouse gas differs in its ability to absorb heat in the atmosphere. atmosphere. HFCsHFCs and and PFCS are the most heatPFCS are the most heat--absorbent. Methane traps over 21 times heat per molecule than absorbent. Methane traps over 21 times heat per molecule than carbon dioxide, and nitrous oxide absorbs 270 times more heat pecarbon dioxide, and nitrous oxide absorbs 270 times more heat per molecule than r molecule than carbon dioxide. Often, estimates of greenhouse gas emissions arecarbon dioxide. Often, estimates of greenhouse gas emissions are presented in units of presented in units of millions of metric tons of carbon equivalents (MMTCE), which weimillions of metric tons of carbon equivalents (MMTCE), which weights each gas by its ghts each gas by its GWP value, or Global Warming Potential.GWP value, or Global Warming Potential.


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Natural GasNatural Gas

Natural gas is a combustible, gaseous mixture of simple hydrocarNatural gas is a combustible, gaseous mixture of simple hydrocarbon compounds, bon compounds, usually found in deep underground reservoirs formed by porous rousually found in deep underground reservoirs formed by porous rock. Natural gas is ck. Natural gas is fossil fuel composed almost entirely of methane, but does contaifossil fuel composed almost entirely of methane, but does contain small amounts of n small amounts of other gases, including ethane, propane, butane and pentane.other gases, including ethane, propane, butane and pentane.

The prevailing scientific theory id that natural gas was formed The prevailing scientific theory id that natural gas was formed millions of years ago millions of years ago when plants and try sea animals were buried by sand and rock. Lawhen plants and try sea animals were buried by sand and rock. Layers of mud, sand, yers of mud, sand, rock and plant and animal matter continued to build up until therock and plant and animal matter continued to build up until the pressure and heat from pressure and heat from the earth turned them into petroleum and natural gas.the earth turned them into petroleum and natural gas.


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Steam Methane Reformer (SMR)Steam Methane Reformer (SMR)

Refineries have a voracious appetite for hydrogen. Depending on Refineries have a voracious appetite for hydrogen. Depending on the refinery the refinery operations, it may necessary to have a hydrogen plant. In a hydroperations, it may necessary to have a hydrogen plant. In a hydrogen plant, hydrogen ogen plant, hydrogen is produced by the reforming of a hydrocarbon feedstock with steis produced by the reforming of a hydrocarbon feedstock with steam. The best am. The best feedstock for this is methane.feedstock for this is methane.

Reformer.Reformer. The reformer is basically a huge furnace that contains tubes fiThe reformer is basically a huge furnace that contains tubes filled with nickel lled with nickel catalyst. The feed is a mixture of steam and methane and the reacatalyst. The feed is a mixture of steam and methane and the reaction in the reformer ction in the reformer is carried out at 650 to 1000 is carried out at 650 to 1000 ooCC and 600 and 600 psipsi. the primary reforming reaction is:. the primary reforming reaction is:

CH4 + H2O CH4 + H2O --> 3H2 + CO> 3H2 + CO

However, some CO2 is also formed in the reformer. Typical yieldsHowever, some CO2 is also formed in the reformer. Typical yields in the reformer in the reformer effluent are 75% H2, 15% CO and 10% CO2.effluent are 75% H2, 15% CO and 10% CO2.


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Shift Convert.Shift Convert. The shift converter is designed to produce more hydrogen by reaThe shift converter is designed to produce more hydrogen by reacting the cting the CO from the reformer with more steam according to the following CO from the reformer with more steam according to the following reaction:reaction:

CO + H2O CO + H2O --> CO2 + H2> CO2 + H2

This is a classical reaction that you may have seen referred to This is a classical reaction that you may have seen referred to as the as the ““water gas shiftwater gas shift””. . It is carried out at 425 It is carried out at 425 oCoC over an ironover an iron--oxide catalyst. Frequently, the shift convert oxide catalyst. Frequently, the shift convert consists of a high temperature and low temperature and low tempeconsists of a high temperature and low temperature and low temperature section. The rature section. The low temperatures section converts the remainder of the CO to CO2low temperatures section converts the remainder of the CO to CO2 by taking advantage by taking advantage of favorable equilibrium for this exothermic reaction.of favorable equilibrium for this exothermic reaction.

Amine Contactor.Amine Contactor. The CO2 is removed from the shift convert effluent by scrubbingThe CO2 is removed from the shift convert effluent by scrubbing in an in an amine contractor like that described in the section on Natural Gamine contractor like that described in the section on Natural Gas Processing. The as Processing. The product of the Scrubber contains traces of CO and CO2 in a highlproduct of the Scrubber contains traces of CO and CO2 in a highly concentrated y concentrated hydrogen stream.hydrogen stream.


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MethanatorMethanator.. Even traces of CO and CO2 in the hydrogen product can poison thEven traces of CO and CO2 in the hydrogen product can poison the catalyst e catalyst of downstream processes or build up in recycle streams. Thereforof downstream processes or build up in recycle streams. Therefore, the CO and CO2 e, the CO and CO2 must be converted to CH4 in the must be converted to CH4 in the methanatormethanator according to:according to:

CO + 3H2 CO + 3H2 --> CH4 + H2O> CH4 + H2OCO2 + 4H2 CO2 + 4H2 --> CH4 + 2H2O> CH4 + 2H2O

The effluent stream from the The effluent stream from the methanatormethanator is about 98% H2 and 2% CH4 and is ready to is about 98% H2 and 2% CH4 and is ready to be used in processes where hydrogen is required.be used in processes where hydrogen is required.


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Synthesis gasSynthesis gas

A mixture of carbon dioxide, carbon monoxide and hydrogen formerA mixture of carbon dioxide, carbon monoxide and hydrogen formerly made by using ly made by using water gas and reacting to with steam to enrich the portion of hywater gas and reacting to with steam to enrich the portion of hydrogen for use in the drogen for use in the synthesis of ammonia. The synthesis gas can be used for producinsynthesis of ammonia. The synthesis gas can be used for producing power and/or g power and/or hydrogen, methanol, Fischerhydrogen, methanol, Fischer--TropschTropsch liquids, etc.liquids, etc.

In a gasification process, a feedstock is heated to very high teIn a gasification process, a feedstock is heated to very high temperatures (100 mperatures (100 oCoC to to 1500 1500 oCoC) under pressure (20 bar to 85 bar) in the presence of controlle) under pressure (20 bar to 85 bar) in the presence of controlled amounts of d amounts of stream and pure oxygen. Two sets of reactions occur in the stream and pure oxygen. Two sets of reactions occur in the gasifiergasifier..

CnHmCnHm + (n2)O2 + (n2)O2 --> > nCOnCO + (m/2)H2+ (m/2)H2CO2 + C CO2 + C --> 2CO> 2COC + H2O C + H2O --> CO + H2> CO + H2

CO + H2O CO + H2O --> CO2 + H2> CO2 + H2

In addition to CO, H2 and CO2, small amounts of CH4, HCL, HF, COIn addition to CO, H2 and CO2, small amounts of CH4, HCL, HF, COS, NH3 and HCN are S, NH3 and HCN are also formed. H2S is also formed with the amount dependent on thealso formed. H2S is also formed with the amount dependent on the sulfur content of sulfur content of the feedstock.the feedstock.


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Pressure Swing Adsorption (PSA)Pressure Swing Adsorption (PSA)

Combined with our engineering upgrades, this field experience haCombined with our engineering upgrades, this field experience has enabled PSA units s enabled PSA units that are flexible and reliable. They have a high turndown ratio that are flexible and reliable. They have a high turndown ratio and can maintain both and can maintain both recovery and product purity by automatically adjusting cycle timrecovery and product purity by automatically adjusting cycle times. Absorbents are es. Absorbents are selected according to the nature of the impurities that need to selected according to the nature of the impurities that need to be removed from the be removed from the hydrogenhydrogen--containing streams and their capacity to offer a long cycle lifecontaining streams and their capacity to offer a long cycle life..

PSA units can be designed to achieve up to 99.9999% hydrogen purPSA units can be designed to achieve up to 99.9999% hydrogen purity. Hydrogen ity. Hydrogen recovery can vary between 50% and over 95%. The result is a funcrecovery can vary between 50% and over 95%. The result is a function of the purity of tion of the purity of the incoming stream, offthe incoming stream, off--gas pressure and recycling. Operating pressures range gas pressure and recycling. Operating pressures range between 5 and 50 bar. Hydrogen is usually recovered with a minimbetween 5 and 50 bar. Hydrogen is usually recovered with a minimal pressure loss of 1 al pressure loss of 1 bar. bar.

module 14. “life cycle assessment (lca)” 4 steps of … steps of lca, approaches, software,...

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