Post on 17-Feb-2018
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