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Thermal treatment
Hans-Peter KoschitzkyVEGAS, University of Stuttgart
May 16th, 2013
Thermal treatment | 2 Hans‐Peter Koschitzky
Why in-situ thermal remediation, ISR ?
Basics of thermal technologies
Operating windows
A successful example of steam-air-injection
Therefore ISR - Conclusions
What you can expect
Thermal treatment | 3 Hans‐Peter Koschitzky
Groundwater table▼
DNAPLdensity > waterDNAPL
LNAPLdensity < water
LNAPL
NAPL = Non-aqueous phase liquid (not miscible with water)
Remediation technologies needed
LNAP – DNAPL problem
Thermal treatment | 4 Hans‐Peter Koschitzky
T2 = 70°CT1 = 20°C
ca. 2 cm
Why thermal treatment ?
Photos: A. Winkler
Thermal treatment | 5 Hans‐Peter Koschitzky
5
SVE“cold”
InjectionSteam High Temperature
TreatmentThermal Enhancement
(e.g. Geodesorb, Joule Resistance Heating)
surface tension σ
viscosity ν
density ρ
temperature
vapour pressure pi
σ, ρ
, ν,
pi
T1 = 20°C
T2 = 70°C
Photos: A. Winkler
Fluid properties - f(Temp)
Thermal treatment | 6 Hans‐Peter Koschitzky
Eutectic Temperature (boiling point of binary mixure), "steam distillation (McCabe-Thiele)"
0
100
200
300
400
500
600
700
800
900
1000
0 20 40 60 80 100 120
[°C]
Vap
our P
ress
ure
[mba
r]
0
100
200
300
400
500
600
700
800
900
1000
Vap
our p
ress
ure
[mba
r]
BenzeneTrichloroetheneWatero-XylenePerchloroethene1,2,3-TrimethylbenzeneNaphtalenepex - pw
Increasing temperature: 20°C 80°Cand vapour pressure• Water: factor 20• PCE: factor 15• Xylene: factor 19
Reduction of boiling point by steam distillation (azeotropic point):
Benzene 80 69°CTCE 87 74°CPCE 121 87°Cm-Xylene 144 93°C
Steam distillation
Thermal treatment | 7 Hans‐Peter Koschitzky
Thermal In-situ TechnologiesConvection Conduction Ohm di-electric
Steam- / Steam-Air -
Injection
Electric Resistance
Heating
RF- / Radio-frequency Heating
Conductive Heating,
Thermal Wells (electric or hot
gas)organic compounds (LNAPL & DNAPL)
increase of vapor pressure of contaminant by heating of subsurface / steam distillation
by factors enhanced extraction rates
Extraction of contaminants as gas (SVE Soil Vapour Extraction)
fast and reliable (and controllable) remediation process selection of technique dependent on site conditions and
“composition“ of contaminants (mixtures)expert knowledge required
Thermal treatment | 8 Hans‐Peter Koschitzky
Operating Windows
Thermal treatment | 9 Hans‐Peter Koschitzky
Steam – Air – Injection (SAI)
Thermal treatment | 10 Hans‐Peter Koschitzky
CharacteristicsOperation windows
DNAPL and LNAPL, light and medium volatile, boiling points < 180°C
UZ: Unconsolidated soil, mean to good permeability (silt gravel)
GZ: Pore aquifer (sand to silt) kf: 5 x 10-5 to 1 x 10-3 m/s
Thermal radius of influence (groundwater)Permeability: 0,5 – 5 x 10-4 m/s Steam propagation: 3 - 5 m radius for 150 kg/h steam Advantage: anisotropic soil structure
FeaturesSimultaneous remediation of aquifer and unsaturated soil zonePossible structural changes in highly organic soil structures (peat layers) settlements?
Thermal treatment | 11 Hans‐Peter Koschitzky
Conductive Heating (Thermal Wells)
Thermal treatment | 12 Hans‐Peter Koschitzky
CharacteristicsOperation windows
DNAPL and LNAPL, light and heavy volatile, boiling points < 250°C
UZ: Low permeable soil layers (fine sediments, silt, clay, … ), permeability up to 10-9 m/s
GZ: For special conditions feasible, to be proved by pilot investigations
Distance of heating elements in the range of meter (function of site)
FeaturesDuring drying of the soil permeability for SVE can significantly increaseBeware of possible settlements (clay layers,…)Low operating and maintenance costs
Thermal treatment | 13 Hans‐Peter Koschitzky
generator Match-box380 V
50 Hz
T > 250°Cpossible
13.56 MHz
- Direct heat generation in the soil volume - High flexibility (temperature programmes)- Can be applied for dry and humid, sandy and tenaceous materials, e.g. soils
OH
Hδ+ δ− δ− δ+
- + + -OH
Hδ+ δ− δ− δ+
- + + -
Comparable to Microwave ovenHeating by internal frictionDipole (e.g. water) or other polare structurs are activated by vibration
Principle of heating
From Dr. Ulf Roland
Radio Frequency / RF Heating
Thermal treatment | 14 Hans‐Peter Koschitzky
Guidelines and tools
Tool for Design Steam-air-injection
Thermal treatment | 15 Hans‐Peter Koschitzky
Impressions from the site in 2005
Field case: Steam-Air-Injection
Thermal treatment | 16 Hans‐Peter Koschitzky
Slaughterhouse of 1574
Dry cleaner
Site Karlsruhe Durlach
Thermal treatment | 17 Hans‐Peter Koschitzky
Historical City Karlsruhe Durlach
Thermal treatment | 18 Hans‐Peter Koschitzky
Groundwater contamination:plume: > 300 mPCE concentration up to 350 µg/L
O. Trötschler, H.-P. Koschitzky, Steffen Ochs, Stephan Denzel
Contaminant source PCEFormer dry cleaner: Leaking sewage system below the historical building
PCE in the unsaturated zone, capillary fringe and saturated zone (silt, clay 5 m b.g.s.)PCE max. 3.800 mg/kg in vadose zone 60 mg/l in groundwater
Contamination
Thermal treatment | 19 Hans‐Peter Koschitzky19
S-A-injection:
7- 8 m b. g.s. max. 200 kg/h
SVE:
100 - 150 m³/h
GW-pumping (cooling water)
1- 3 m³/h
Geology / remediation concept
Thermal treatment | 20 Hans‐Peter Koschitzky
E 4 (S2)EK 3 (S1) E 2 (S1)
EK 1 (S1)
E 8 (S4)
EK 9 (S4)E 10 (S4)
E 7 (S2)
EK 5 (S2)
EK 11 (S4)SI 3.2 SI 2.2
SI 1.2
SI 1.1SI 2.1
SI 3.1
B 7
(GW-Infiltration)E 12
SI 4.1
-8 m
-8 m
-8 m
-8 m
-8 m
-8 m
-8 m
-8 m
-3,0 m
-7 m-7 m
-7 m
-7 m
-7 m
-7 m
BLA-Hor
T1T2T3T4T5T6
T7
T-E4
T9 T11T10
T-EK5
T8
T14T13
T12
T-Hor16 St. Pt100
T-EK1
T-E2T-EK3
T-E7
T-EK11
T-E10T-EK9
T-E8
-5m
-5m -5m
-5m
-3,5m
-3,5m
SI 4.2Hor-16
Hor-15Hor-14
Hor-13Hor-12
Hor-11Hor-10
Hor-9Hor-8
Hor-7Hor-6
Hor-5Hor-4
Hor-3Hor-2
Hor-1
-3,5m
SI 4.2
SI 3.1
SI 3.2
SI 2.1
SI 2.2 SI 1.1
SI 1.2
-7m
© dplan, ZUT, VEGAS
Site owner: Stadt Karlsruhe
Remediation planning and contracting:consultant dplan (& VEGAS)
Operation:Züblin Umwelttechnik
Scientific assistancy, monitoring and remediation control:VEGAS & dplan
Advisory boardRP-Ka, City of KA, EPA (LUBW) of Baden-Württemberg
1234
VEGASVersuchseinrichtung zur Grundwasser- und Altlastensanierung
Remediation: implementation
Thermal treatment | 21 Hans‐Peter Koschitzky
E 2,4,8,10 bzw. EK 1,3,9SI 1-4.2SI 1-4.1
BLA-Brunnen
Wirkungsbereich DL-InjektionWirkungsbereich DL-Injektion
A'A - SÜD
Auffüllung
GW-Spiegel
︵Fundament proj. ︶
- 1 , 0
- 3 , 0
- 2 , 0
- 8 , 0
- 1 0 , 0
- 9 , 0
- 7 , 0
- 6 , 0
- 5 , 0
- 4 , 0
GasTelefon Strom Wasser
K o m b i - B r u n n e n
B L A - B r u n n e n
" A n d e r S t a d t m a u e r "
H a u s
B L A - H O R
B o d e n p l a t t e
1 1 6 , 6 5 m ü N N
0 1 m 2 m 3 m 4 m 5 m
U , f s
f S - m S
G , m - g S
Soil
vapo
ur
Gro
undw
ater
Soil
vapo
ur
Gro
undw
ater
GW-Spiegel
Steam ZoneSteam Zone
injection wells temperature
monitoring
build
ing
fillings
fine sand
Coarse sand
steamed zonerange of steam
NG supplyTelecommunicationpower lineswater supplyGroundwater table
Combined wells SVE and groundwater
soil vapour wells
SVE wells
SAI below the building
Thermal treatment | 22 Hans‐Peter Koschitzky
Photo: Steffen Hetzer, ZUT Photo: Steffen Hetzer, ZUT Photo: Steffen Hetzer, ZUT
Drilling and installation of wells
Thermal treatment | 23 Hans‐Peter Koschitzky
Groundwater and soil vapour extraction,activated carbon filter
Exhaust chimny SVE
Extraction well and temperature measurement
Field installation: remediation
Thermal treatment | 24 Hans‐Peter Koschitzky
Temperature development during remediation
Thermal treatment | 25 Hans‐Peter Koschitzky
Heat propagation: compartment 2
Thermal treatment | 26 Hans‐Peter Koschitzky
Contaminant removal by SVE
Thermal treatment | 27 Hans‐Peter Koschitzky
Development of CHC in groundwater
Thermal treatment | 28 Hans‐Peter Koschitzky
• Total duration incl. drilling works 70 weeks
• Duration of remediation 42 weeks (ca. 30 weeks steam-air injection)
• Contaminant removal mass 500 kg CHC (incl. pilot)
Summary and some numbers of remediation (1)
• Remediation goals achieved concerning CHC concentration (10 mg/m³ in soil vapour, << 10 µg/L in groundwater)
• Impressive reduction of groundwater contamination- before: 60.000 µg/L- two years after: < 5,0 µg/L down to not detectable
Thermal treatment | 29 Hans‐Peter Koschitzky
• costs total budget ca. 600.000 €- 25% drilling and construction- 25% consumables, energy (mainly gas for steam production)- 50% for plants installation and operation
specific costs: ~ 180 €/to soil
• Energy balance: 470 kWh/m³ soil (84% heat; 16% electric)total consumption: 780 MWh (thermal energy)
153 MWh (electrical energy)
Summary and some numbers of remediation (2)
Thermal treatment | 30 Hans‐Peter Koschitzky
The site after the remediation (15.11.2011)
Thermal treatment | 31 Hans‐Peter Koschitzky
Therefore ISR
ISR can used under difficult and narrow conditions (even below buildings)ISR reduce remediation time at minimum by one order of magnitudeISR can reduce the total energy consumption by a factor 2Cost for subsurface heating and on site treatment (Soil vapour and groundwater) are approx. similar
Thermal treatment | 32 Hans‐Peter Koschitzky
Conclusion
ISR can help to solve our contamination problemsBut - no “universal” remedy existsuse ISR carefully expert knowledge is needed
Detailed site information is needed to chose an optimum solutionInvest money in a serious site investigationInvest in (lab experiments, special problems) and pilots
Both will save money and at least led to a cost andeco efficient and sustainable solution
Thermal treatment | 33 Hans‐Peter Koschitzky
http://www.vegas.uni-stuttgart.de
Dr.-Ing. Hans-Peter Koschitzky & Oliver TrötschlerVEGAS, Versuchseinrichtung zur Grundwasser- und Altlastensanierung, Universität Stuttgart
… at the very end