screw pyrolysis of sewage sludge 1 session1.1/1...1 16.11.2016 marco tomasi morgano screw pyrolysis...

Institute for Technical Chemistry (ITC)

Dept. Pyrolysis / Gas Treatment

1 16.11.2016 Marco Tomasi Morgano

Screw Pyrolysis of Sewage Sludge: A Techno-economic AnalysisKIT – The Research University in the Helmholtz Association

Symposium on Thermal and Catalytic Sciences for Biofuels and Biobased Products

November 1 – 4, 2016 – The Friday Center, University of North Carolina, Chapel Hill

www.kit.edu

Screw Pyrolysis of Sewage Sludge:

A Techno-economic Analysis

Marco Tomasi Morgano, Hans Leibold, Frank Richter, Helmut Seifert, Dieter Stapf




Screw Pyrolysis of Sewage Sludge: A Techno-economic Analysis

Sewage sludge production – EU vs. USA

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Spec

ific

sew

age

slu

dge

pro

du

ctio

n [

kg/p

.e./

year

]

Sew

age

slu

dge

pro

du

ctio

n [

10

3to

n D

S/ye

ar] Sewage Sludge Production

Specific Sewage Slude Production

• EU Data from A. Kelessidis, A.S. Stasinakis / Waste Management 32 (2012) 1186-1195

• USA Data from www.nviro.com/files/Biosolids_Facts.pdf (production of Biosolids 2004) and US Census Bureau (US population 2004)

http://www.nviro.com/files/Biosolids_Facts.pdf





Sewage sludge utilization – EU vs. USA

• EU Data from A. Kelessidis, A.S. Stasinakis / Waste Management 32 (2012) 1186-1195

• USA Data from King County / 2012 – 2016 Biosolids Plan Appendix B (June 2012)

41

19

17

12

12

EU-27

36

15

30

6

13

USA





Motivation

New German Sewage Sludge Regulation 2025 (AbfklärV).

Recovery of phosphorus in bioavailable form will be mandatory.

More stringent toxicological limits will be given.

Agricultural use will be forbidden





Waste Water Treatment Plants

in Baden-Württemberg

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25000R

enq

uis

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erst

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arin

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/Vö

hri

nge

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nst

ein

-Leo

po

ldsh

afen

Ellw

agen

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ckac

h

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nen

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stad

t

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ters

tein

-Alb

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f

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ön

aich

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l am

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ein

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tkir

ch

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inge

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sulm

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tatt

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knag

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nz-

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mb

ach

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un

linge

n

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bu

rg-F

orc

hh

eim

Kar

lsru

he

Man

nh

eim

Stu

ttga

rt-M

üh

lhau

sen

Cap

acit

y [t

on

(DS)

/y]

1000 ton (DS)/y

data from Umweltbundesamt (2013) / Sewage sludge management in Germany





Approach

Feedstock characterization and experimental investigations at bench-scale for products distribution and properties.

Thermodynamic design of the

pyrolysis-based process.

Modelling and Scale-up of the reactor.

Cost estimation of major components.

Evaluation of selected scenarios and determination of “Break-even” price of char.





Pre-dried sewage sludge characterization

Ultimate analysis wt.% (d.b.) Halogens wt.% (d.b.)

C H N S Cl F

30.2 4.3 4.8 1.2 0.15 0.03

Proximate analysis wt.% (a.r.) Heating value (MJ/kg) (a.r.)

Moisture Ash (550°C) Volatile Matter Fixed Carbon HHV LHV

10.0 38.1 48.8 3.1 12.1 11.0

Ash composition wt.% of ash

SiO2 Al2O3 CaO MgO P2O5 Na2O K2O SO3

29.1 9.7 12.7 1.9 16.0 0.4 1.3 3.7

Metals concentration mg/kg (d.b.)

This Study Sewage Sludge* Soil*

Antimony Sb 8 - -

Arsenic As 6.3 18 -

Lead Pb 59 150 40 - 100

Cadmium Cd 1.1 3 0.4 - 1.5

Chromium Cr 260 120 30 - 100

Cobalt Co 9 - -

Copper Cu 420 800 20 - 60

Manganese Mn 840 - -

Nickel Ni 110 100 15 - 70

Mercury Hg 0.49 2 0.1 - 1

Thallium Th < 0.2 1.5 -

Zinc Zn not measured 1800 60 - 200

Vanadium V 36 - -*data from Umweltbundesamt (2013) / Sewage sludge management in Germany

d.b. is dry basis

a.r. is as received





Bench-scale reactor STYX

Screw

Ceramic

Filter

Feedstock

Pyrolysis

char

Vapors

+

Gas

Electrically

Heated

Trough

Filter

elements

Char

samples

Reactor Data

Flow Rate < 10 Kg/h

Temperature < 600 °C

Residence Time 2.5 - 40 Min

Heated Length 2000 mm

Screw Diameter 150 mm

Filtration Data

N° Elements 2 – 14

Length 200 mm

Diameter 60 mm

Material SiC

Online Recleaning

Operation Data

Time (2012-2015) 3000 h

Material (2012-2015) 7,5 tons

Main Feedstocks:

Wood, Wheat Straw, Sewage Sludge,

Chicken Manure, Litter, Oil Sand, etc.





STYX reactor





Sewage sludge pyrolysis

Char/solid is always the main product.

Minerals retained in the char.

Chars contain some volatiles.

Water phase is ammonia solution.

Heterogeneous aromatics in the oil.

Sulfur in the gas-phase as H2S.

LHVCHAR < 10 MJ/kg.

LHVOIL > 28 MJ/kg.

Chemical energy products > 90%.

Process requirements = 450 kJ/kgFEED.

Energy distribution on LHV basis.

Mass yields on feedstock basis.

Ash





Configuration 1 – combustion of vapors

Vapors at pyrolysis temperature are incinerated.

Hot flue gases are used to heat the pyrolysis reactor.

Four sub-configurations:

Only Heat: after the reactor, hot water is produced.

Only ORC: after the reactor, electricity is produced in ORC motor (Organic Rankine Cycle).

EF-MGT+Heat: electricity (Externally Fired Micro Gas Turbine) and hot water (Heat).

EF-MGT+ORC: electricity (EF-MGT) and electricity (ORC).

N2

Char

Pyrolysis

reactor G

Air

Micro gas turbine

Pyrolysis vaporsFeedstock

Local heatCombustion airFlue gases

External

combustion

chamber

Local heat –

heat exchanger

HT-Heat exchanger

Recuperator

Configuration 1C: EF-MGT + Heat.





Configuration 2 – condensation of vapors

Pyrolysis vapors are condensed, separated and stored before utilization.

Permanent gases and water-like phase are injected in the combustion chamber for the

heating of the pyrolysis reactor.

Part of the pyrolysis oil is combusted to achieve the capacity of the pyrolysis reactor .

Pyrolysis oil is used in the Oil-MGT (Oil - Micro Gas Turbine).

Two sub-configurations:

Oil-MGT+Heat: electricity (ORC-MGT) and hot water (Heat).

Oil-MGT+ORC: electricity (Oil-MGT) and electricity (ORC).

Configuration 2B: Oil-MGT + ORC.

N2

Pyrolysis

reactor

external

combustion

Flue gasesCombustion air

Char

G

ORC -

Process

G

Air

Condensation

unit

Oil tank

Sewage sludge Pyrolysis vaporsPermanent

gases &

water-phase

Oil

external

combustion

chamber

Recuperatorμ-GT

flue gases

Oil-MTG

Burner

Micro Gas Turbine

Mixer





Thermodynamic balance

Plant Configuration (450°C) Only Heat Only ORCEF-MGT +

Heat

EF-MGT +

ORC

Oil-MGT +

Heat

Oil-MGT +

ORC

Char [kg/h] 95,3 95,3 95,3 95,3 95,3 95,3

Electric Power [kW] - 49,7 50,9 84,8 47,9 70,7

Local Heat [kW] 152,7 - 107,4 - 76,5 -

Electric Efficiency [%] - 9,9 10,2 17,0 9,6 14,1

Thermal Efficiency [%] 30,5 - 21,5 - 15,3 -

CHP Efficiency [%] 30,5 9,9 31,7 17,0 24,9 14,1

Plant Configuration (500°C) Only Heat Only ORCEF-MGT +

Heat

EF-MGT +

ORC

Oil-MGT +

Heat

Oil-MGT +

ORC

Char [kg/h] 92,4 92,4 92,4 92,4 92,4 92,4

Electric Power [kW] - 62,2 54,6 99,8 59,5 88,7

Local Heat [kW] 190,9 - 143,7 - 95,9 -

Electric Efficiency [%] - 12,4 10,9 20,0 11,9 17,7

Thermal Efficiency [%] 38,2 - 28,7 - 19,2 -

CHP Efficiency [%] 38,1 12,4 39,6 20,0 31,1 17,7

Thermal input of 500 kWT.

Mass flow of pre-dried (10 wt.-% H2O) sewage sludge of 173 kg/h.





Reactor scale-up

STYX bench-scale 500 kW Scaled-up

Mass flow 4 kg/h Mass flow 173 kg/h

Residence time 10 minutes Residence time 20 minutes

Heating Isothermal electric Heating Co-current gas

Requirements 1 kW Requirements Ca. 45 kW

Length 2 m Length 5 m

Diameter 0.15 m Diameter 0.50 m

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Techno-Economic framework (Germany)

Cost estimation of the main equipment based on capacity factors.

Feedstock costs 90% DM = 40€ (dewatering, drying and preparation).

Operation cost = 5% of capital costs.

Investment costs with Plant factor 2.

Price of heat based on natural gas price.

Three scenarios for electricity price.

Basis: price at the Leipzig European Energy Exchange.

Feed-In EEG: price for electricity from renewable energy.

Internal Utilization: price for internal production and utilization of electricity.

Determination of a “break-even” price for the char and comparison with

potential markets.

Gas cleaning equipment not yet considered.





Investment costs

Pyrolysis reactor (1/3 to 1/2 of total investment).

EF-MGT includes high temperature heat exchanger (1000°C).

External combustion chamber more expensive in configuration with vapors.

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Only Heat Only ORC EF-MGT +Heat

EF-MGT +ORC

Oil-MGT +Heat

Oil-MGT +ORC

Inve

stm

ent

cost

s [€

]

Pyrolysis Reactor Combustion Chamber Condensation UnitTank Local Heat - Heat Exchanger Oil-MGTEF-MGT ORC

Investment costs for

nominal pyrolysis

temperature 450°C.





Costs & Revenues

Feedstock costs (dewatering, thermal drying, preparation, etc.) 1/4 to 1/3 of total costs.

Heat more valuable than electricity → power is a “cheap” product.

None of the configurations survives selling heat and electricity.

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-50,000

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EF-MGT +ORC

Oil-MGT +Heat

Oil-MGT +ORC

Co

sts

/ R

even

ues

[€

/y]

Feestock costs Annuity Operation costs Local heat ElectricityCost and Revenues for nominal

pyrolysis temperature 450°C.





Char “break-even“ price

Only Heat “needs” the lowest price.

Larger heat & power plants → higher char price.

Power is “expensive” to produce.

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250

300

350


EF-MGT +ORC

Oil-MGT +Heat

Oil-MGT +ORC

Ch

ar “

bre

ak-e

ven

” p

rice

[€

/to

n]

350°C400°C450°C500°C

Ash Landfilling

Struvite

H2S Adsorbents

Char “break-even” prices for

the six pyrolysis-based plants.





Alternative scenarios

Only Heat still convenient in scenario “Feed-In EEG”.

Combined heat & power better than full electric in scenario “internal utilization”.

Char price reduced by a factor 2 in configuration EF-MGT + ORC.

0

50

100

150

200

250

300


EF-MGT +ORC

Oil-MGT +Heat

Oil-MGT +ORC

Ch

ar “

bre

ak-e

ven

” p

rice

[€

/to

n]

Basis Feed-In EEG Int. UtilizationChar “break-even” price in alternative scenarios

for nominal pyrolysis temperature 450°C.





Conclusions & Outlook

Products yields and properties on experimental basis at bench-scale.

Sewage sludge NOT suitable for direct agricultural use (heavy metals).

Two basic set-up with and without condensation of pyrolysis vapors for

electric efficiency up to 20% on LHVFEED basis (EF-MGT + ORC).

Reactor scale-up based on experimental validation of numerical model.

Pyrolysis reactor most important investment.

None of the configuration is rentable without char valorization.

Heat production → lower char «break-even» price (H2S adsorbents).

Internal utilization of heat and power most favorable scenario.





Thank You for Your attention

Contact:

Marco Tomasi Morgano

Phone: +49 721 608 22869

Email: [email protected]

Karlsruhe Institute of Technology (KIT)

Institute for Technical Chemistry

Dept. Pyrolysis / Gas Cleaning

Hermann-von-Helmholtz-Platz-1

76344 Eggenstein-Leopoldshafen (D)

screw pyrolysis of sewage sludge 1 session1.1/1...1 16.11.2016 marco tomasi morgano screw pyrolysis...

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