Advanced Technologies for Desulphurisation of Coke Oven Gas

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1 Advanced Technologies for Desulphurisation of Coke Oven Gas Frank Sowa, Bjoern Otten, Johannes Kamp DMT GmbH & Co. KG, Cokemaking Technology Division, Am Technologiepark 1, Essen, Germany Emanuele Proface Paul Wurth Italia S.p.A., Via di Francia 1, Genova, Italy COG Desulphurisation ICC 2009, Ranchi, India Seite 1

2 Alternative Ways of Using COG Gas Cleaning Utilisation Underfiring in Coke Oven Battery or Steel Work Heat Utilisation for industrial heat production Cleaned Coke Oven Gas (COG) from By Product Plant 1. COG fine cleaning of NH3 and H2S compounds 1. COG fine cleaning 2a. Pressure Swing Adsorption 2b. Steam Reforming Electricity Generation by - Gas Engine -Gas Turbine - HT Fuel Cell Raw material for the chemical industry - Fischer-Tropsch- Synthesis Increase of Valuability Electricity Raw Material 1. COG fine cleaning 2a. Pressure Swing Adsorption Hydrogen for the mobility sector - Fuel cell driven cars & buses - LNG driven vehicles High Grade Fuel 2b. Steam Reforming 3. Shift Conversion to produce Hydrogen Hydrogen for the home sector - Fuel cell appliances COG Desulphurisation ICC 2009, Ranchi, India Seite 2

3 Purity Requirements for COG Utilisation NH 3 (mg/nm 3 COG) H 2 S (mg/nm 3 COG) HCN (mg/nm 3 COG) Coke Oven Underfiring < < < Industrial Boilers < < < Gas Motor < 15 < unspecified Low efficient Gas Turbine unspecified < 500 unspecified High efficient Gas Turbine < 0,3 < 1,2 < 7,0 (e.g. for Combined Cycle) HT Fuel Cell < 0,5 < 2,0 < 150 Fischer Tropsch Synthesis < 1 ppmv H 2 S + COS + CS 2 < 1 ppmv < 1 ppmv COG Desulphurisation ICC 2009, Ranchi, India Seite 3

4 Survey of desulphurisation processes Wet Oxidation Route Absorption / Stripping Route Stretford H 2 S is scrubbed from the coke oven gas by a sodium carbonate solution (Na 2 CO 3 ) and elemental sulphur (S ) is yielded using vanadate (VO 3 ) as an intermediate. Regeneration of the scrubbing liquid takes place by aeration (O 2 ), using anthraquinone disulphonic acid (ADA) as an intermediate. ASK or Diamex H 2 S is scrubbed from the coke oven gas by a NH 3 solution. The NH 3 solution is derived from the NH 3 scrubber. The H 2 S and NH 3 are stripped from the washing liquor by steam stripping and the vapours are led to a Claus plant or a sulphuric acid plant. Takahax Thylox Perox Fumaks-Rhodacs Vaccuum Carbonate Sulfiban DESULF COG Desulphurisation ICC 2009, Ranchi, India Seite 4

5 General Comparison of both Process Routes Wet Oxidation Route Absorption / Stripping Route Better desulphurisation efficiency of ca. 99.9% achieving residual H 2 S concentrations as low as 1 mg/nm 3 in the COG. Removal of most of the hydrogen cyanide from the COG forming sodium thiocyanide which 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 Nm 3 /h COG. Absorptive processes usually do not exceed 95% desulphurisation efficiency achieving residual H 2 S concentrations in the COG of ca. 300 mg/nm 3. The discharge of small wastewater flows to the BET does not require any further treatment. Applicable at new and existing plants COG Desulphurisation ICC 2009, Ranchi, India Seite 5

6 Plant Configuration for TCO Wet Oxidation Process Absorption / Stripping Process Coal Water COG 6 g H2S / Nm3 6 g NH3 / Nm3 COG 6 g H2S / Nm3 6 g NH3 / Nm3 NaOH Coal Water Coal Water Stripper NaOH Ammoniumsulphate Stretford H2SO4 (NH4)2SO4 Na2CO3 Vanadate ADA Tartrate Sulphur ASK* Stripper / Deacidifier Claus Sulphur Wastewater to Biological Treatment Purge stream to special wastewater treatment COG 2 mg H2S / Nm3 30 mg NH3 / Nm3 COG 300 mg H2S / Nm3 30 mg NH3 / Nm COG Desulphurisation ICC 2009, Ranchi, India Seite 6

7 Assumptions / Parameters of the TCO elaboration (on European basis) 1/3 Parameter Ammonia Sulphate / ASK / Stripper / Stretford Claus Plant COG production Nm 3 /h 42,000 42,000 Crude COG H 2 S g/nm NH 3 g/nm Clean COG H 2 S mg/nm NH 3 mg/nm COG Desulphurisation ICC 2009, Ranchi, India Seite 7

8 Assumptions / Parameters of the TCO elaboration (on European basis) 2/3 Price of Parameter Ammonia Sulphate / ASK / Stripper / Consumables Stretford Claus Consumables /t Steam t/d /kwh Electricity kwh/d 11,900 6, /t H 2 SO 4 (98%) t/d /kg ADA kg/d /kg Vanadate kg/d /kg Tartrate kg/d /t Soda t/d /t Caustic Soda t/d COG Desulphurisation ICC 2009, Ranchi, India Seite 8

9 Assumptions / Parameters of the TCO elaboration (on European basis) 3/3 Parameter Ammonia Sulphate / ASK / Stripper Stretford / Claus Plant Products Sulphur t/d Ammonium Sulphate t/d Revenues Sulphur /t Ammonium Sulphate /t Annual Debt Service on Capital Costs % Annual Maintenance on Capital Costs % COG Desulphurisation ICC 2009, Ranchi, India Seite 9

(Solidified Sample after S-Separator) 21.01.

10 Sulphur Quality Stretford Sulphur (Solidified Product after Autoclave) Claus Sulphur (Solidified Sample after S-Separator) COG Desulphurisation ICC 2009, Ranchi, India Seite 10

11 TCO comparison (incl. costs for steam) 1,75 ct/nm³ COG 1,50 1,25 0,59 0,48 Δ = 0.06 ct/nm 3 COG 6.5 % Categories 1,00 0,75 0,98 ct/nm³ COG 0,54 0,14 0,92 ct/nm³ COG Revenues Energy Chemicals Maintenance Debt Service 0,50 0,50 0,10 0,25 0,00 0,10 0,11 0,28 0,30 Stretford 1 ASK / Stripping 2 Ammoniumsulphate Claus COG Desulphurisation ICC 2009, Ranchi, India Seite 11

12 TCO comparison (without costs for steam) 1,75 ct/nm³ COG 1,50 1,25 1,00 0,75 0,40 0,50 0,48 0,80 ct/nm³ COG Δ = 0.19 ct/nm 3 COG 31 % 0,23 0,14 Categories Revenues Energy Chemicals Maintenance Debt Service 0,50 0,25 0,10 0,10 0,11 0,28 0,30 0,61 ct/nm³ COG 0,00 Stretford 1 ASK / Stripping 2 Ammoniumsulphate Claus COG Desulphurisation ICC 2009, Ranchi, India Seite 12

13 Sale Scenario Impact on TCO Sale Scenario Process Route Cleaning Costs ct/ Nm 3 COG Scenario (NH 4 ) 2 SO 4 /t S /t Scenario (Steam at costs) Δ Scenario (Steam at no costs) Δ Medium level Stretford ASK % % High level Stretford ASK % % Low level Stretford ASK % % COG Desulphurisation ICC 2009, Ranchi, India Seite 13

14 Conclusions Wet Oxidation Route Absorption / Stripping Route Advantages: High cleaning efficiency (<2 mg H 2 S / Nm 3 COG, 30 mg NH 3 / Nm 3 COG) No HP-scrubbing required Disadvantages: Higher operating costs NH 3 and HCN pre-scrubbing required Catalyst as consumable required Quality of Sulphur S often deteriorated yielding lower revenues Contaminated wastewater streams need special treatment Susceptible for contamination Dependence on suppliers for catalyst and ADA (consumables) Advantages: Lower operating costs No consumable catalyst required NH 3 -scrubbing included High quality Sulphur S with high revenues No contaminated wastewater; wastewater directly delivered to the BET Disadvantages: Lower cleaning efficiency (300 mg H 2 S / Nm 3 COG, 30 mg NH 3 / Nm 3 COG) HP-scrubbing necessary to achieve a H 2 S concentration of below 2 mg/nm 3 in the clean gas (if demanded) COG Desulphurisation ICC 2009, Ranchi, India Seite 14

15 Thank you for your attention! COG Desulphurisation ICC 2009, Ranchi, India Seite 15

MODERN COKE OVEN GAS TREATMENT TECHNOLOGY AT A NEW COKE MAKING PLANT IN BRAZIL*

MODERN COKE OVEN GAS TREATMENT TECHNOLOGY AT A NEW COKE MAKING PLANT IN BRAZIL* Wolfgang Kern 1 Mario Petzsch 2 Antonio Esposito 3 Helênio Resende Silva Júnior 4 Abstract The implementation of the Gas