USE  OF  ALTERNATIVE  FUELS  IN  CEMENT  PRODUCTION  (con%nuing  study)  Nickolas  Themelis  and  Marco  Castaldi  

Earth  Engineering  Center,  Columbia  University  and  City  College  of  New  York    

WTERT  2014  MeeDng,  October  20,  2014  

www.wtert.org 2 2

 GLOBAL  WTERT  COUNCIL  (2014)  

www.wtert.org

www.wtert.ca

www.wtert.cn

www.wtert.eu

www.wtert.com.br

www.wtert.jp

www.mater.polimi.it/mater/

www.wtertuane.com.mx/

http://wtert.in

www.wtert.co.uk

Some of the more active GWC members

We welcome today our newest member: WTERT-Chile (Prof. Alex Godoy of

Universidad del Desarollo, Santiago)

www.wtert.org 3

The  Global  WTERT  Council  (GWC)  

•  to identify the best available technologies for the treatment of

various “waste” materials •  to recover materials and energy from “waste”materials §  to conduct academic research on sustainable waste

management §  to disseminate this information by means of publications, the

multilingual WTERT web pages, and periodic meetings and conferences, at the national and international levels

§  to provide high level education on Sustainable Waste Management

For example: This meeting!

Objectives of WTERT Global Council (GWC)

www.wtert.org 4

The  Global  WTERT  Council  (GWC)  At this meeting you heard papers on Reduction (South Korea), Recycling (VBWF), Landfill Gas utilization, waste-to-fuels and waste-to-energy

•  Energy can be recovered from wastes by: •  Combustion in WTE plants (about 10% of the U.S, post-

recycling MSW goes to WTE plants; but 90% still goes to landfills)

•  But: Energy can also be recovered by using “wastes” in industrial processes in place of fossil fuels

•  With the help of CEMEX, an international cement company headquartered in Monterey, Mexico, GWC is examining the use of “waste” fuels in cement production

CEMEX Corporation

•  Presence in 50 countries •  43,000 employees •  94 million tons of cement/year •  New York City office •  Cement plant visited by authors: Balcones (San

Antonio, Texas) •  Cement production is, by far, the largest worldwide

high temperature process –  Use of fossil fuels: Typically, 3.6 MJ/kg of cement

“clinker”

The Cement Process (Jiao Zhang Thesis, Columbia, 2013) Overall

Additives

Clinker

Tertiary air Calciner

Rotary kiln

Calcined solid Primary air

Clinker Clinker cooler

Clinker silo Mill

Portland cement silo

Air

Secondary air

Flue gas

Raw material

Mixed raw material

Raw mill

Raw meal silo

Preheater tower

Baghouse

Stack

Solid flow Gas flow

Raw material silo

Flue gas

Fuel flow

Fuel 1

Fuel 3

Fuel 2

Preheated solid

Raw meal

Cooler exhaust gas

Figure 3-1 Flow sheet of cement production process

Best integrated process • Multiple places for fuel addition

• Determined by feed system • Chemical content of AF is important • Thermal integration helps

• Gas flow counter-current to solids • Self-cleaning process

• Size and preparation of fuel important

Solids Flow

Gas Flow

Gas Flow

Cement Production Worldwide

Source: Cement” in U.S. Geological Survey, 2012, Mineral Commodity summaries 2012: U.S. Geological Survey, 198p.

Impacts of Cement Production •  CO2, CO, NOx & SO2

–  200 kg of coal per tonne of cement

–  900-1000 kg CO2 per tonne of clinker (~5% of total GHG emissions)

•  60 % is related to calcination of CaCO3, remainder is fuel combustion.

•  NOx emissions amount to ~0.3-4.7 kg/tonne of clinker

•  US cement clinker production 78 million tons in 2010

•  Global cement production: 3.5 billion tons

•  Hypothetically, 50% use of Alternative Fuels would utilize 350 million tons (175% of current WTE capacity)

Use of Alternative Fuels in cement industry

•  In 2009 the cement industry recovered 16.3 million tonnes of waste •  The use of fossil waste grew fast between 1990 and 2000, whereas

biomass grew fast since 2000 and continues

Dat

a fro

m th

e C

SI “

Get

ting

the

Num

bers

Rig

ht”

syst

em

2602

6283 8782

11412

337

1225

3833

4901

0

4000

8000

12000

16000

20000

1990 2000 2005 2009

CSI + CEMBUREAU Global volume of fossil waste & biomass

Biomass

Fossil waste kton

nes/

year

Source: CEMBUREAU March 2012 – Global Fuels Conference & Exhibition

Alternative fuel usage in Cement Kilns

Kiln  2     Eng.Fuel   Wood   Tires   Bottom  Ash  

Pecan  Shells  

Other   Sum  

Apr-­‐13   19.6%   18.5%   12.8%   1.9%   0.7%   0.0%   53.5%  Feb-­‐13   15.2%   18.3%   12.2%   2.3%   0.6%   0.1%   48.7%  

 

CEMEX Alternative Fuel Usage • Engineered fuel, tires and biomass • 38.9% Jan – April 2013 •  Avg US from 1993-2001, à 10%-15%

Representation of the AF mixture High Pet Coke replacement achieved

US Average 700,000 tons of EF utilized •  reduced GHG by 1% in US •  5.2% increase in WTE capacity •  280,000 tons of ash used

14.6 MMtonnes estimated US max Increases WTE capacity by 110%

Fossil Fuels

Alternative Fuels

“Engineered Fuel”: Non-marketable residue of Materials Recovery Facilities (MRF) consisting of a

mixture of plastics and paper

Engineered Fuel (EF) Fluff Engineered Fuel (EF) extruded pellet

Samples of EF collected by Themelis and Castaldi at Balcones Plant

Emissions

• Hg emission was 0.000014 mg/Nm3

•  Dioxin ~0.01 ng TEQ/Nm3 (an order of magnitude below E,U./U.S. standard)

• Inherent advantage: Presence of CaO makes cement production a self-scrubbing process that sequesters chlorine.

• The chlorine input in the fuel is limited only by possible operational problems (chloride accretions in calciner or pre-heater)

  EU  standard  after  conversion  to  7%  O2  in  stack  gas  

Emissions   Combustion  plants  

kilns    

  mg/Nm3        mg/Nm3  

Total  dust   23.32   38.19  HCl   10.0   12.73  HF   1.0   1.273  NOx   187   636.5  Cd+Tl   0.05   0.06365  Hg   0.05   0.06365  Sb+As+Pb+Cr+Co+Cu+Mn+Ni+V  

0.05   0.6365  

SO2   233   63.65  TOC     12.73  CO   50.0   89.0    

10

Modeling Effort of Gases •  Development of reaction mechanism (GRI modification) •  Simulate different fuels and scenarios •  Find a suitable mixture minimizing emissions

⎟⎠

⎞⎜⎝

⎛ −=RTEATk n expRate = k CfuelCox

Eact n A Example of sulfur reactions

Chlorine reactions

Elementary Reaction step A n Eact

Pre-calcined material enters kiln

500

3000

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16Time(s)

Temperature(K)

Modeling Effort of Gases

Combustion gas flow

Elementary step mechanism anchored by combustion gas residence time (15 seconds)

CEMEX à Kiln outlet temperature Calc à adiabatic flame temperature

Region modeled

Residence time

Tem

pera

ture

HCl,  Kiln

0.0E+00

5.0E-­‐04

1.0E-­‐03

1.5E-­‐03

2.0E-­‐03

2.5E-­‐03

3.0E-­‐03

3.5E-­‐03

4.0E-­‐03

0 0.2 0.4 0.6 0.8 1 1.2

distance

mole  fractio

n

pet  coke

wood

tires

EF

RDF HCl,  Calciner

0.E+00

1.E-­‐05

2.E-­‐05

3.E-­‐05

4.E-­‐05

5.E-­‐05

6.E-­‐05

7.E-­‐05

8.E-­‐05

0 0.2 0.4 0.6 0.8 1 1.2distance

mole  fractio

n

RDF

tires

pet  coke

EF

wood

Chlorine Higher concentrations in Kiln Once formed, remains constant Cl2 increase toward exit end •  cement kiln dust •  corrosion

HCl/Cl2 Kiln Profile

0.00000

0.00005

0.00010

0.00015

0.00020

0.00025

0.00030

0.00035

0.00040

0.00045

0.00050

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Residence Time (s)

HC

l Mol

e/cm

3

0.00E+00

1.00E-08

2.00E-08

3.00E-08

4.00E-08

5.00E-08

6.00E-08

Cl2 mole/cm

3

HCl

Cl2

Continuing Research: Nour Awad, MS Thesis, Columbia and CCNY

Jiao Zhang – MS Thesis, Columbia University Alexandros Karaiskakis – MS/PhD, City College of New York Flavia Albuquerque – CCNY (Visiting Scholar, from Rio de Janeiro State University) -

Earth Engineering Center Columbia University and City College of New York

Acknowledgements