an integrated process for hydrogen production from solid ... · from solid fuel gasification. ......

An Integrated Process for Hydrogen Production from Solid Fuel Gasification1

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S4FE, Roma6-10 July 2009

CPR – Consorzio Pisa Ricerche – ITALYDivisione Energia Ambiente

UNIPI – Università di Pisa – ITALYDipartimento di Ingegneria Chimica

S4FE - Sustainable Fossil Fuels for Future Energy

Rome, 6-10 July 2009Presentation

CPRBiaginiEnrico

AffiliationAuthors

CPRMasoniLorenzo

UNIPITognottiLeonardo

CPRBruminiDario

An Integrated Process for Hydrogen Production An Integrated Process for Hydrogen Production

from Solid Fuel Gasificationfrom Solid Fuel Gasification


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CPR / UNIPI CPR / UNIPI –– Process study activitiesProcess study activities

* entrained flow reactors;

* hot gas desulfurization;

* sour WGSR.

Hydrogen production

from gasification of

coals and blends

coal/biomass

Collaboration with ENEL (x RegioneVeneto)

MATT project

* oxyfiring combustor;

* Air Separation Unit.

Optimization of

oxyfiring process of

coal for CCS

PRIN

Carbone pulito

* fixed bed gasifier;

* PSA / polymeric membranes

for hydrogen separation.

Hydrogen production

from gasification plant

of biomasses with

oxygen/steam

MIUR / RegioneToscana

Filiera Idrogeno

* fluidized bed gasifiers;

* dual bed pyrolyzer;

* tar cracking reactor;

* metallic membranes.

Hydrogen production

from gasification plant

of biomasses and

coals, integrated with

power plant

FISR

Integrated Systems forHydrogen Production and Use in DistributedGeneration

Specific modelsActivityProject


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FilieraFiliera IdrogenoIdrogenoProject funded by Regione Toscana

CPR/UNIPI contribution in the project is related to the production of hydrogen:

• Quantification of electric energy from renewable source (wind,PV,

geothermy) and biomass availability in Tuscany;

• Selection of hydrogen production technologies;

• Optimization of the production process

Valdera

Main tasks:

• Production

• Transportation

• Storage

• Utilization

of hydrogen from renewable sources in a district near Pisa (Valdera).

Hydrogen produced is used in two kinds of cars:

• fuel cell cars

• internal combustion engine cars


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Hydrogen from renewable sourcesHydrogen from renewable sources

Using hydrogen as an energy carrier can help mitigate the discontinuous

availability of renewable energy sources by providing opportunities for storage.

Electrolysis:

• H2 purity: >99.99%

• Utilization: Fuel Cells

Biomass gasification:

• H2 purity: >99%

• Utilization: Combustion process

Electrolysis Gasification


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Biomass gasificationBiomass gasification

Small biomass gasifiers generally utilize air as oxidant, because of the

relatively high cost of oxygen production at a small scale.

Oxygen gasification vs air gasification:

-Syngas with low nitrogen content (higher LHV), which leads to an

easier H2 separation;

- Reduced plant dimension;

- Power required for syngas compression before the separation is lower.


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Scope of the workScope of the work

A detailed process study of biomass gasification is performed for optimizing the hydrogen production.

1. Process description

2. Development of the detailed process simulation model

3. Optimization of the equipment design and the operating conditions

4. Results and discussion


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The Integrated Process The Integrated Process

Electrolyzer

water

electrolyte

Oxygen

Gasifier

Ash

Syngas

Dryer

high purity hydrogen (>99.99%)

(steam)

CO shift

reactors

Waste water

(tar and ash)

water (basic)

H2 separation(PSA or membranes)

CO2 for recycle or sequestration

Stack

Biomass

treatment

Biomass

medium purity

hydrogen (>99%)

electricity production

electricity

wind

Scrubber

Engine

Geothermal plant

Oxygen produced by elecrolysis using wind and geothermal electric power

- Configuration 1:

gasifier with cooling jacket for steam production;

- Configuration 2:

gasifier consideredadiabatic, heat recovery from retentatecombustion.

Steam produced by thermal recovery from the plant:


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Procedure for gasifier model Procedure for gasifier model

developmentdevelopment

* in spite of the differences in gasification plants, most process studies

in the literature modeled the gasifier as an equilibrium reactor. This

approach is indeed fundamental for a preliminary study but hardly

suitable for process analysis and optimization procedures.

* definition of the functional scheme of the gasifier;

* separation of the characteristic steps of solid fuel gasification

(devolatilization, oxidation, gasification of the char, homogeneous

reactions and tar cracking);

* development of sub-models of each step (by adapting conventional

blocks or implementing structural models as ABCD for solid fuel

devolatilization);

* connection of all steps to respect the material and heat balances

according to the gasifier configuration.


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Functional scheme of the gasifierFunctional scheme of the gasifier

Drying

Devolatilization

Combustion

Gasification

[Lv, Renewable Energy 2007]

Devolatilization

Sub-model

(ABCD Db)

pre-heating

/ drying

pre-heating

Biomass

nitrogen

steam

oxygen

Combustion

Sub-model

(PFR)

Gasification

Sub-model

(PFR)

Heat

Balance

Steam

production

steam

syngas

ash /solid

dispersion


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SubSub--model development devolatilizationmodel development devolatilization

ABCD (Advanced Biomass and Coal Devolatilization) model

Starting approach: CPD Chemical Percolation Devolatilization model (Fletcher 1992)

improvements: * revised relations in the code (available free of charge)

by CPR-EA * extension to biomass fuels

* population balance of n-mers formed during pyrolysis evolution

* elemental balance closure

* secondary reactions (tar-cracking and cross-linking)

input – structural parameters of the fuel and operating conditions (P, T(t))

output – pyrolysis macro-products (char, metaplast, tar, light gas)

gas speciation: CO2, CO, H2O, CH4 (original version)

+ heteroatom species

+ H2, C2H4


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SubSub--model development devolatilizationmodel development devolatilization

+ population balance

+ elemental balance+ secondary reactions

Solid fuel(coal, biomass, blend) characteristic

data

ABCD fuel

parameters

ChemicalPercolation

Devolatilization

Thermal history

Macro-products

chartargas

OUTPUT

Gas Speciation

Chemical

composition

Data available?

Azevedo [2002] Correlation

CelluloseHemicell.Lignin

Y N

BIOMASS

Hypotheses on cellulose and

hemicellulosecomposition

Lignin composition

from element balance

Ultimate

analysis

ABCD fuel

parameters

NMR

analysis

Ultimate

analysis

Y N

Data available?

Genetti [1999] Correlation

C O A LBLEND

xbiomass + ycoal

Mcl: Molecular Weight per cluster

Md: Molecular Weight side chain

(σ+1): Coordination Number per cluster

p0: Fraction of intact bridges

Scheme of the ABCD

model: main blocks and

procedure for the

evaluation of structural

parameters of the fuels


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Implementation of the ABCD model Implementation of the ABCD model

in the process modelin the process model

ASPENPLUS

user routine

Pyrolysis

databaseABCD model

P 30 600 700 800 900 1000 1100 1200

%CHAR 0.86175 0.759791 0.639926 0.567876 0.535924 0.523774 0.521401

%TAR 0.043701 0.09107 0.147301 0.154399 0.153443 0.156768 0.156703

%H2O 0.043985 0.059999 0.076545 0.081232 0.077125 0.074294 0.073613

%CO2 0.008107 0.009847 0.014094 0.022014 0.024399 0.02797 0.028835

%CH4 0.024501 0.042932 0.060049 0.079533 0.093639 0.096888 0.097849

%CO 0.001679 0.00626 0.015833 0.027761 0.031121 0.030938 0.030896

%HCN 0.001688 0.003688 0.006356 0.007561 0.008287 0.008694 0.008792

%H2S 0.000114 0.000277 0.000557 0.000966 0.001219 0.001289 0.00131

%COS 0.001102 0.002299 0.003721 0.0039 0.003876 0.00396 0.003958

off-line simulationsT = 600 – 1600 °CP = 10 – 40 bar

(T,P)

interpolation of data and normalization


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SubSub--model development model development –– further stepsfurther steps

Model of combustion unitModel of combustion unit

ASPENPLUS

Rplug block

Main combustion reactions:

C + ½ O2 → COCO + ½ O2 → CO2CH4 + 2O2 → CO2 + 2H2OC2H2 + 5/2 O2 → 2CO2 + H2OH2 + ½ O2 → H2Otar + O2 → CO2 + H2O

Reactions of main species

Global kinetics

Isothermal reactor

Hypothesis on residence time

Model of gasification unitModel of gasification unit

Main gasification reactions:

C + H2O → CO + H2C + CO2 → 2COC + 2H2 → CH4

CH4 + H2O → CO + 3H2CO + H2O → CO2 + H2

Reactions of main species

Heterogeneous kinetics

(unreacted core-shrinking model)

Adiabatic reacton


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Syngas treatment modelsSyngas treatment models

• the scrubber is modeled as an absorption column (RadFrac)

• the Water Gas Shift Reactor is composed two catalytic beds

operating in different conditions (RPlug with User kinetic from literature

works)

• the hydrogen separation with Pd-based membrane is modeled by

programming a multi-tube metal membrane customized library.

Characteristic parameters for H2 permeation are derived from the

properties of the commercial membrane produced by ATI Wah Chang.

Hydrogen permeation flux expression:

( )n

lH

n

hHHHPPJ

,2,222−℘=


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Model results Model results Hypothesis for the reference conditionsHypothesis for the reference conditions

atm1Syngas pressure permeate

membranes

bar25Syngas pressure inlet membranes

°C200Syngas temperature inlet membranes

°C180-220Syngas temperature inlet 2nd WGSR

°C350-400Syngas temperature inlet 1st WGSR

mol/mol3H2O/CO inlet shift section

°C40Syngas temperature after scrubber

bar3Steam produced in the gasifier

°C1000-

1200

Maximum temperature in the gasifier

wt/wt0.05Nitrogen feed/fuel

kg/h250Biomass flowrate

atm1Gasifier pressure

atm3.8Outlet pressure of electrolysis plant

kWh/Nm3 of

H2

5Electricity consumption of the

electrolyzer

%mol99.99H2 purity from electrolysis plant

%mol99.99O2 purity from electrolysis plant


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Model results Model results Gasifier H2 efficiencyGasifier H2 efficiency

Configuration 1: Gasifier with cooling jacket for steam production

0.10

0.15

0.20

0.25

0.30

0.82 0.84 0.86 0.88 0.9 0.92 0.94 0.96

rO/C

ηη ηηG

0.00

0.50

1.00

1.50

2.00

2.50

rSt/C

gasifie

r

Tgasifier 1000°C Tgasifier 1100°C Tgasifier 1200°C

BiomBiom

HGH

G

HVW

HVW2,2

=ηNet hydrogen efficiency of the gasifier

W = flowrate; HV = heating value


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Model results Model results Gasifier H2 efficiencyGasifier H2 efficiency

Configuration 2: Gasifier considered adiabatic

0.10

0.15

0.20

0.25

0.30

0.58 0.6 0.62 0.64 0.66 0.68 0.7

rO/C

ηη ηηG

0.00

0.50

1.00

1.50

2.00

2.50

rSt/C

ga

sifie

r


BiomBiom

HGH

G

HVW

HVW2,2




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Model results Model results H2 efficiency of the gasifierH2 efficiency of the gasifier

0.10

0.15

0.20

0.25

0.30

0.35

800 900 1000 1100 1200 1300

T gasifier (°C)

ηη ηηG

rO/C = 0.69

0.640.59

0.94

0.890.84

rO/C = 0.79

CONF1

CONF2

BiomBiom

HGH

G

HVW

HVW2,2




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Model results Model results H2 efficiency of the plantH2 efficiency of the plant

0.25

0.30

0.35

0.40

0.45

0.50

0.58 0.6 0.62 0.64 0.66 0.68 0.7

rO/C

ηη ηηP

1.00

1.50

2.00

2.50

3.00

3.50

4.00

rSt/C

pla

nt


Configuration 2

BiomBiom

HPH

P

HVW

HVW2,2

=η Net hydrogen efficiency of the plantW = flowrate; HV = heating value


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Model results Model results H2 production from the entire systemH2 production from the entire system

0

2

4

6

8

10

12

14

460 480 500 520 540 560

PO + PE (kW)

H2 p

rod

uc

ed

(k

g/h

)

H2 (99%) from gasification

H2 (99.99%) from electrolysis

Electricity Electricity Oxygen Steam Hydrogen Hydrogen

Electrolysis Gasification consumed consumed Electrolysis Gasification

kW kW kg/h kg/h kg/h kg/h

420 54.4 60 153.5 7.50 11.75

455 54.5 65 170.5 8.13 11.93

490 53.5 70 191.0 8.75 11.67

Although reported in the table, oxygen and steam consumptions are internal recycles of the system and do not require any input from external sources.


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ConclusionsConclusions

• Hydrogen is a clean and valuable energy carrier which can be used

successfully in distributed utilizations. Its production from renewable sources

needs process studies for evaluating the technical and economical feasibility.

• An integrated process for biomass gasification is studied: two plant

configurations are evaluated by modeling its units and interconnecting them.

The detailed approach we used for developing the process model allows to

evaluate the suitability of the equipment and the feasibility of the process.

• The equipment of the plant is designed and preliminary optimization studies are

conducted, focusing on oxygen and steam internal consumptions.

• A relatively small scale plant (250 kg/hr) fed with poplar wood is used in all

simulations: variations of biomass and plant size will be studied in future works

along with further optimization and economical evaluations.

More details, info, comments:

[email protected]

an integrated process for hydrogen production from solid ... · from solid fuel gasification. ......

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