21.01.2009 | COG Desulphurisation ICC 2009, Ranchi, India | Seite 1 www.dmt.de
Advanced Technologies for Desulphurisation of Coke Oven Gas
Frank Sowa, Bjoern Otten, Johannes KampDMT GmbH & Co. KG, Cokemaking Technology Division,
Am Technologiepark 1, 45307 Essen, Germany
Emanuele ProfacePaul Wurth Italia S.p.A., Via di Francia 1, 16149 Genova, Italy
21.01.2009 | COG Desulphurisation ICC 2009, Ranchi, India | Seite 2 www.dmt.de
Alternative Ways of Using COG
Cleaned Coke Oven Gas (COG) from By
Product Plant
Underfiring in Coke Oven Battery or Steel
Work
Utilisation for industrial heat production
Electricity Generation by- Gas Engine- Gas Turbine- HT Fuel Cell
Hydrogen for the mobility sector
- Fuel cell driven cars & buses
- LNG driven vehicles
Raw material for thechemical industry- Fischer-Tropsch-
Synthesis
1. COG fine cleaning of NH3 and H2S
compounds
1. COG fine cleaning
2a. Pressure Swing Adsorption
2b. Steam Reforming
3. Shift Conversion to produce Hydrogen
1. COG fine cleaning
2a. Pressure Swing Adsorption
2b. Steam Reforming
Gas Cleaning Utilisation
Incr
ease
of V
alua
bilit
y
Heat
Electricity
Raw Material
High Grade Fuel
Hydrogen for the homesector
- Fuel cell appliances
21.01.2009 | COG Desulphurisation ICC 2009, Ranchi, India | Seite 3 www.dmt.de
Purity Requirements for COG
< 500 – 1000< 300 – 500< 10 – 200Industrial Boilers
< 150< 2,0< 0,5HT Fuel Cell
< 7,0< 1,2< 0,3High efficient Gas Turbine (e.g. for Combined Cycle)
< 1 ppmVH2S + COS + CS2
< 1 ppmV< 1 ppmVFischer Tropsch Synthesis
< 500
< 300 – 500
< 300 – 900
H2S (mg/Nm3 COG)
unspecified< 15 Gas Motor
unspecifiedunspecifiedLow efficient Gas Turbine
< 500 – 1000< 10 – 200Coke Oven Underfiring
HCN (mg/Nm3 COG)
NH3
(mg/Nm3 COG)Utilisation
21.01.2009 | COG Desulphurisation ICC 2009, Ranchi, India | Seite 4 www.dmt.de
Survey of desulphurisation processes
Wet Oxidation Route
StretfordH2S is scrubbed from the coke oven gas by a sodium carbonate solution (Na2CO3) and elemental sulphur (S°) is yielded using vanadate (VO3) as an intermediate. Regeneration of the scrubbing liquid takes place by aeration (O2), using anthraquinonedisulphonic acid (ADA) as an intermediate.
TakahaxThyloxPeroxFumaks-Rhodacs
Absorption / Stripping Route
ASK or DiamexH2S is scrubbed from the coke oven gas by a NH3 solution. The NH3 solution is derived from the NH3 scrubber. The H2S and NH3 are stripped from the washing liquor by steam stripping and the vapours are led to a Claus plant or a sulphuric acid plant.
Vaccuum CarbonateSulfibanDESULF
21.01.2009 | COG Desulphurisation ICC 2009, Ranchi, India | Seite 5 www.dmt.de
General Comparison of both Process RoutesWet Oxidation Route
Better desulphurisation efficiency of ca. 99.9% achieving residual H2S concentrations as low as 1 mg/Nm3 in the COG.Removal of most of the hydrogen cyanide from the COG forming sodium thiocyanidewhich are purged by a liquid stream to prevent salting out of the chemicals.Wastewater usually to be treated separately owing to the presence of compounds showing detrimental effects on the BET.Applicable at new and existing plants.Applicable also for low desulphurisation capacities starting from 400 Nm3/h COG.
Absorption / Stripping Route
Absorptive processes usually do not exceed 95% desulphurisation efficiency achieving residual H2S concentrations in the COG of ca. 300 mg/Nm3.The discharge of small wastewater flows to the BET does not require any further treatment.Applicable at new and existing plants.
21.01.2009 | COG Desulphurisation ICC 2009, Ranchi, India | Seite 6 www.dmt.de
Plant Configuration for TCOAbsorption / Stripping ProcessWet Oxidation Process
ASK* Unit
Stripper / Deacidifier
Unit
COG6 g H2S / Nm36 g NH3 / Nm3
COG 300 mg H2S / Nm330 mg NH3 / Nm3
Claus Unit
Sulphur
Ammonium-sulphate
Unit
COG 6 g H2S / Nm36 g NH3 / Nm3
COG 2 mg H2S / Nm330 mg NH3 / Nm3
Sulphur
Stretford Unit
H2SO4
Na2CO3Vanadate
ADATartrate
(NH4)2SO4
Coal Water
NaOH
Coal Water Stripper Unit
Coal Water
Wastewater toBiological Treatment
Purge stream to special wastewater
treatment
NaOH
21.01.2009 | COG Desulphurisation ICC 2009, Ranchi, India | Seite 7 www.dmt.de
Assumptions / Parameters of the TCO elaboration (on European basis) – 1/3
42,00042,000Nm3/hCOG production
30030
230
mg/Nm3
mg/Nm3
Clean COGH2SNH3
66
66
g/Nm3
g/Nm3
Crude COGH2SNH3
ASK / Stripper Unit / Claus Plant
Ammonia Sulphate / Stretford
UnitParameter
21.01.2009 | COG Desulphurisation ICC 2009, Ranchi, India | Seite 8 www.dmt.de
Assumptions / Parameters of the TCO elaboration (on European basis) – 2/3
11.90 €/t0.34 €/kWh128.00 €/t
7.70 €/kg27.00 €/kg5.50 €/kg
370.00 €/t110.00 €/t
Price of Consumables
2646,600
---------------9.6
15411,90017.52410132.69.6
t/dkWh/d
t/dkg/dkg/dkg/d
t/dt/d
ConsumablesSteam
ElectricityH2SO4 (98%)
ADAVanadate
TartrateSoda
Caustic Soda
ASK / Stripper / Claus Unit
Ammonia Sulphate / Stretford Unit
UnitParameter
21.01.2009 | COG Desulphurisation ICC 2009, Ranchi, India | Seite 9 www.dmt.de
Assumptions / Parameters of the TCO elaboration (on European basis) – 3/3
1111%Annual Debt Service on Capital Costs
250--
125180
€/t€/t
RevenuesSulphur
Ammonium Sulphate
44%Annual Maintenance on Capital Costs
5.4--
4.823.5
t/dt/d
ProductsSulphur
Ammonium Sulphate
ASK / Stripper Unit / Claus Plant
Ammonia Sulphate / Stretford
UnitParameter
21.01.2009 | COG Desulphurisation ICC 2009, Ranchi, India | Seite 10 www.dmt.de
Sulphur Quality
Stretford Sulphur(Solidified Product after Autoclave)
Claus Sulphur(Solidified Sample after S-Separator)
21.01.2009 | COG Desulphurisation ICC 2009, Ranchi, India | Seite 11 www.dmt.de
TCO comparison (incl. costs for steam)
Δ = 0.06 €ct/Nm3 COG≈ 6.5 %
0,28 0,30
0,10 0,11
0,50
0,59
0,54
0,10
0,00
0,25
0,50
0,75
1,00
1,25
1,50
1,75
1 2
RevenuesEnergyChemicalsMaintenanceDebt Service
Categories
0,98 €ct/Nm³ COG
0,92 €ct/Nm³ COG
0,48
0,14
ASK / Stripping UnitClaus Unit
Stretford UnitAmmoniumsulphate Unit
€ct/Nm³ COG
21.01.2009 | COG Desulphurisation ICC 2009, Ranchi, India | Seite 12 www.dmt.de
0,28 0,30
0,10 0,11
0,40
0,23
0,50
0,10
0,00
0,25
0,50
0,75
1,00
1,25
1,50
1,75
1 2
RevenuesEnergyChemicalsMaintenanceDebt Service
Categories
0,80 €ct/Nm³ COG
0,61 €ct/Nm³ COG
0,48
0,14
ASK / Stripping UnitClaus Unit
Stretford UnitAmmoniumsulphate Unit
€ct/Nm³ COG
TCO comparison (without costs for steam)
Δ = 0.19 €ct/Nm3 COG≈ 31 %
21.01.2009 | COG Desulphurisation ICC 2009, Ranchi, India | Seite 13 www.dmt.de
Sale Scenario Impact on TCO
0.610.92ASK250---+64%
1.00
+29%
1.19Stretford---120Low level
0.570.88ASK320---+51%
0.86
+18%
1.04Stretford---180High level
0.610.92ASK250---+31%
0.80
+7%
0.98Stretford125180Medium
level
ΔScenario(Steam at no costs)Δ
Scenario(Steam at costs)
S°€/t
(NH4)2SO4
€/tScenario
Cleaning Costs€ ct / Nm3 COG
ProcessRoute
Sale Scenario
21.01.2009 | COG Desulphurisation ICC 2009, Ranchi, India | Seite 14 www.dmt.de
Conclusions
Wet Oxidation Route
Advantages:High cleaning efficiency (<2 mg H2S / Nm3
COG, 30 mg NH3 / Nm3 COG)No HP-scrubbing required
Disadvantages:Higher operating costs NH3 and HCN pre-scrubbing requiredCatalyst as consumable requiredQuality of Sulphur S° often deteriorated yielding lower revenuesContaminated wastewater streams need special treatmentSusceptible for contaminationDependence on suppliers for catalyst and ADA (consumables)
Absorption / Stripping Route
Advantages:Lower operating costsNo consumable catalyst requiredNH3-scrubbing includedHigh quality Sulphur S° with high revenuesNo contaminated wastewater; wastewater directly delivered to the BET
Disadvantages:Lower cleaning efficiency (300 mg H2S / Nm3 COG, 30 mg NH3 / Nm3 COG)HP-scrubbing necessary to achieve a H2S concentration of below 2 mg/Nm3 in the clean gas (if demanded)
21.01.2009 | COG Desulphurisation ICC 2009, Ranchi, India | Seite 15 www.dmt.de
Thank you for your attention !
