PETCOKE
AS
FUEL FOR CEMENT PRODUCTION
BENEFITS & CHALLENGES
by
Dr J D BAPAT
http://www.drjdbapat.com
CBI INDIA & SOUTH ASI...
PETCOKE
AS
FUEL FOR CEMENT PRODUCTION
WHAT IS PETCOKE
● CONVENTIONAL FUEL: PULVERISED MINERAL COAL
● PETCOKE: A SOLID, CAR...
PETCOKE
AS
FUEL FOR CEMENT PRODUCTION
PETCOKE
AS
FUEL FOR CEMENT PRODUCTION
WHY PETCOKE
● HIGH CALORIFIC VALUE > 8,000 kcal/kg (3500-4500 kcal/kg CONVENTIONAL),...
PETCOKE
AS
FUEL FOR CEMENT PRODUCTION
CEMENT PRODUCTION COST ANALYSIS
BASIS: CONSIDER PROCTION COST AS 100
FUEL 48
POWER 3...
PETCOKE
AS
FUEL FOR CEMENT PRODUCTION
CHARACTERISTICS OF PETCOKE VIS-À-VIS CONVENTIONAL FUELS
FUEL ASH (%) VM (%) S (%) HG...
PETCOKE
AS
FUEL FOR CEMENT PRODUCTION
CHALLENGES IN PETCOKE BURNING
● LOW HARD GROOVE INDEX: DIFFICULT TO GRIND
● LOW VOLA...
PETCOKE
AS
FUEL FOR CEMENT PRODUCTION
CHALLENGES IN PETCOKE BURNING: DIFFICULT TO GRIND
●LOW HGI, HENCE DIFFICULT TO GRIND...
PETCOKE
AS
FUEL FOR CEMENT PRODUCTION
CHALLENGES IN PETCOKE BURNING: DIFFICULT TO BURN
● LOW VOLATILES MAKE PETCOKE DIFFIC...
PETCOKE
AS
FUEL FOR CEMENT PRODUCTION
HIGH-MOMENTUM GRECO BURNER
EXTERNAL AIR
TANGENTIAL AIR
PETCOKE
DISPERSION AIR
COOLIN...
PETCOKE
AS
FUEL FOR CEMENT PRODUCTION
HIGH MOMENTUM BURNER
● OPERATES WITH OUTER, HIGH-MOMENTUM FLOW OF PRIMARY AIR (EXTER...
PETCOKE
AS
FUEL FOR CEMENT PRODUCTION
HIGH MOMENTUM GRECO BURNER: TYPICAL DESIGN PARAMETERS
● PRIMARY AIR PRESSURE 2000 – ...
PETCOKE
AS
FUEL FOR CEMENT PRODUCTION
CHALLENGES IN PETCOKE BURNING: VOLATILE CYCLES
● ALKALIES (K2O/Na2O), LIME FROM RAW ...
PETCOKE
AS
FUEL FOR CEMENT PRODUCTION
CHALLENGES IN PETCOKE BURNING: VOLATILE CYCLES
● SULPHUR-TO-ALKALI RATIO (Q) DECIDES...
PETCOKE
AS
FUEL FOR CEMENT PRODUCTION
CHALLENGES IN PETCOKE BURNING: VOLATILE CYCLES
● TO PREVENT SO2 GAS LEAVE THE KILN, ...
PETCOKE
AS
FUEL FOR CEMENT PRODUCTION
CHALLENGES IN PETCOKE BURNING: VOLATILE CYCLES
●IMPROVING REFRACTORY LINING
● PROVID...
PETCOKE
AS
FUEL FOR CEMENT PRODUCTION
PROBLEMS FACED IN PETCOKE BURNING
● INCREASE IN NOX EMISSIONS: HIGHER CV CAUSES HIGH...
THANKS!!!
drjdbapat.com
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PETCOKE AS FUEL FOR CEMENT PRODUCTION: BENEFITS & CHALLENGES: Dr J D BAPAT

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The GMI Global, LLC, organized a two day conference, Cement Business and Industry (CBI), India and South Asia, at Mumbai, on 9-10 October 2013. The venue was Hilton International Airport Hotel. Dr J D Bapat gave a presentation on “Petcoke as Fuel for Cement production: Benefits and Challenges”. Good number of Indian and international organisations were represented in the Conference, some of which are mentioned below:

Lafarge India
CW Group
Afghan Ministry of Mines
Magnesita
Claudius Peters Projects GmbH
Ultratech Cement
RNCOS Business Consultancy
Ambit Capital
National council for Cement and Building Materials
HGH Systems
Task force for Business and Stability Operations, US Department of Defense
Geicycle Business, ACC
PwC India
Shree Cement
RNB Cement
DPTS Enterprises
Reliance Cement
World Business Council for Sustainable Development
Zuari cement
Prism Cement
Tata Strategic Management Group

The Indian Cement Industry today prefers petcoke as an alternate fuel for cement manufacturing for various reasons. The important among them are as follows:

(a) High calorific value > 8,000 kcal/kg (3500-4500 kcal/kg conventional), low ash content and low volatile matter (but high sulphur content, up to 7%)
(b) Resource conservation thru production of higher grade cement or utilisation of marginal and low grade raw materials
(c) Saving in transport cost due to lesser fuel load
(d) Saving in the initial cost (fuel cost constitutes about 48% of the cost of cement production)

However the burning of petcoke also throws some challenges, like:

(a) Low hard groove index: difficult to grind
(b) Low volatile matter: difficult to burn
(c) High sulphur: Condensation of sulpahtes and chlorides in preheater section results in jamming of process flows, termed as volatile cycles

Dr Bapat, in his presentation, discussed how these challenges are effectively met by the cement industry. The delegates actively participated in q/a session, that followed.

Published in: Technology, Business
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  • Sujay! Thanks for the comment. The data given in the presentation refers to high momentum burners (Greco type) with inlet velocity in the range of 35-45 m/s. You may like to refer ZKG 08/2012 issue, which mentions a ratio of 5 kg fuel/kg air. The ratio works out to same after calculation for Nm3
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  • The Fuel : Air ratio mentioned above does not look correct for Pet Coke combustion. It has to be 1 : 10 - 15 (kg Pet coke : Nm3 air), i believe. In Furnace oil it is 1 : 10 - 12. What is the correct ratio in Pet coke ?
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PETCOKE AS FUEL FOR CEMENT PRODUCTION: BENEFITS & CHALLENGES: Dr J D BAPAT

  1. 1. PETCOKE AS FUEL FOR CEMENT PRODUCTION BENEFITS & CHALLENGES by Dr J D BAPAT http://www.drjdbapat.com CBI INDIA & SOUTH ASIA OCTOBER 9-10, 2013, MUMBAI
  2. 2. PETCOKE AS FUEL FOR CEMENT PRODUCTION WHAT IS PETCOKE ● CONVENTIONAL FUEL: PULVERISED MINERAL COAL ● PETCOKE: A SOLID, CARBONACEOUS RESIDUE PRODUCED BY THERMAL DECOMPOSITION OF HEAVY PETROLEUM FRACTIONS OR CRACKED STOCKS, OR BOTH (ASTM 2005). PETCOKE TYPES RELEVANT FOR CEMENT PRODUCTION: ● GREEN DELAYED PETCOKE: PRIMARY SOLID CARBONIZATION PRODUCT FROM HIGH BOILING HYDROCARBON FRACTIONS OBTAINED AT TEMP OF 475- 490 C, OVER EXTENDED PERIODS OF 12-36 h (.) CONTAINS 4-15% VOLATILES (IUPAC 1995) (.) DELAYED PROCESS COKE IS PRODUCED BY A SEMI- CONTINUOUS BATCH PROCESS & ACCOUNTS FOR MAJORITY OF COKE PRODUCTION. ● FLUID PETCOKE: PRODUCED BY CONTINUOUS FLUIDIZED BED PROCESS (.) TYPICALLY CONTAINS LESS VOLATILE MATTER THAN DELAYED PROCESS GREEN COKE (2.5-6%) ● IUPAC: INTERNATIONAL UNION OF PURE AND APPLIED CHEMISTRY
  3. 3. PETCOKE AS FUEL FOR CEMENT PRODUCTION
  4. 4. PETCOKE AS FUEL FOR CEMENT PRODUCTION WHY PETCOKE ● HIGH CALORIFIC VALUE > 8,000 kcal/kg (3500-4500 kcal/kg CONVENTIONAL), LOW ASH CONTENT & LOW VOLATILE MATTER (BUT HIGH SULPHUR CONTENT, UP TO 7%) ● RESOURCE CONSERVATION THRU PRODUCTION OF HIGHER GRADE CEMENT OR UTILISATION OF MARGINAL & LOW GRADE RAW MATERIALS ● SAVING IN TRANSPORT COST DUE TO LESSER FUEL LOAD ● SAVING IN INITIAL COST
  5. 5. PETCOKE AS FUEL FOR CEMENT PRODUCTION CEMENT PRODUCTION COST ANALYSIS BASIS: CONSIDER PROCTION COST AS 100 FUEL 48 POWER 36 RAW MATERIALS 14 STORAGE 2 -------------------------------------------- TOTAL 100
  6. 6. PETCOKE AS FUEL FOR CEMENT PRODUCTION CHARACTERISTICS OF PETCOKE VIS-À-VIS CONVENTIONAL FUELS FUEL ASH (%) VM (%) S (%) HGI CV (kcal/kg) PETCOKE 0.4-1.0 2.5-15 6-7 37-45 8200-8300 BITUMINOUS COAL (I) 25-40 24-30 0.5-0.9 60-65 3500-4500 BITUMINOUS COAL (IMP) 7-15 25-31 0.6-1.0 48-50 6500-7000 LIGNITE 18-20 30-32 2-3 40-48 8000-8200 I = INDIA & IMP = IMPORTED
  7. 7. PETCOKE AS FUEL FOR CEMENT PRODUCTION CHALLENGES IN PETCOKE BURNING ● LOW HARD GROOVE INDEX: DIFFICULT TO GRIND ● LOW VOLATILE MATTER: DIFFICULT TO BURN ● HIGH SULPHUR: CONDENSATION OF SULPAHTES AND CHLORIDES IN PREHEATER SECTION RESULTING IN JAMMING OF PROCESS FLOWS, TERMED AS VOLATILE CYCLES
  8. 8. PETCOKE AS FUEL FOR CEMENT PRODUCTION CHALLENGES IN PETCOKE BURNING: DIFFICULT TO GRIND ●LOW HGI, HENCE DIFFICULT TO GRIND ●REQUIRES FINER GRINDING DUE LOW VOLATILES: 1.5% ON 90 MICRON (INSTEAD OF CONVENTIONAL 15% ON 90 MICRON) ● POSSIBLE SOLUTION: ● TO REDUCE RESIDUE: INCREASE AIR SEPARATOR RPM IN VRM (.) TYPICAL: REPLACING DIRECT DRIVE WITH V-BELT PULLEY DRIVE ● TO INCREASE VRM OUTPUT: REDUCE MILL INTERNAL DIA (.) TYPICAL: 40% REDUCTION (.) LOWER OUTPUT PARTLY COMPENSATED BY HIGHER CALORIFIC VALUE ● FOR STABLE & UNIFORM BED FORMATION: INCREASING DAM RING HEIGHT, WATER SPRINKLING & REDUCING TABLE SPEED
  9. 9. PETCOKE AS FUEL FOR CEMENT PRODUCTION CHALLENGES IN PETCOKE BURNING: DIFFICULT TO BURN ● LOW VOLATILES MAKE PETCOKE DIFFICULT TO BURN i.e. LATE IGNITION & LONGER FLAME ● HENCE PROPER MIXING OF FUEL & AIR ESSENTIAL ● IMPROPER BURNING CAN RESULT IN POOR QAULITY CLINKER ● POSSIBLE SOLUTION: ● USE HIGH MOMENTUM BURNER: TYPICAL – GRECO BURNER
  10. 10. PETCOKE AS FUEL FOR CEMENT PRODUCTION HIGH-MOMENTUM GRECO BURNER EXTERNAL AIR TANGENTIAL AIR PETCOKE DISPERSION AIR COOLING AIR MIXING AIR
  11. 11. PETCOKE AS FUEL FOR CEMENT PRODUCTION HIGH MOMENTUM BURNER ● OPERATES WITH OUTER, HIGH-MOMENTUM FLOW OF PRIMARY AIR (EXTERNAL AIR) (.) HIGH MOMENTUM AND HIGH EXIT VELOCITY (IN JETS) RESPONSIBLE FOR THE SLIM, FIRM SHAPE OF BURNER FLAME ● SWIRLING AIR (TANGENTIAL AIR & DISPERSION AIR) INTENSIVELY MIX PULVERIZED COAL RESULTING IN RAPID & STABLE FLAME FORMATION ● SHORTER & RADIENT FLAME ● Nox REDUCED DUE TO LOW PRIMARY AIR AT HIGH MOMENTUM ● FLAME GEOMETRY EASY TO CONTROL, AS SEEN FROM KILN SHELL THERMAL PROFILE ● ALL BURNER CHANNELS ARE SEPARATELY ADJUSTABLE & THEIR FUNCTION CAN BE CLEARLY FOLLOWED ● GRECO BURNER IS DESIGNED TO MINIMISE WEAR
  12. 12. PETCOKE AS FUEL FOR CEMENT PRODUCTION HIGH MOMENTUM GRECO BURNER: TYPICAL DESIGN PARAMETERS ● PRIMARY AIR PRESSURE 2000 – 5000 mm WG ● PRIMARY AIR EXCESS FACTOR 4 – 10% ● FUEL CONVEYING AIR 2.5 – 3.5% OF STOICHIMETRIC AIR ● FUEL/AIR RATIO 3.2 – 6 kg/Nm3 AIR ● SPECIFIC BURNER MOMENTUM* 6 – 14 N/MW BURNER THERMAL POWER *NOTE: SPECIFIC BURNER MOMENTUM = (PRIMARY AIR MASS FLOW, kg/s) (PRIMARY AIR VELOCITY, m/s) / (BURNER THERMAL POWER, MW )
  13. 13. PETCOKE AS FUEL FOR CEMENT PRODUCTION CHALLENGES IN PETCOKE BURNING: VOLATILE CYCLES ● ALKALIES (K2O/Na2O), LIME FROM RAW MEAL & SO2 FROM PETCOKE BURNING CAN COMBINE IN COLDER ZONES, NAMELY IN KILN INLET & RISER DUCT TO FORM COATING (.) COATINGS EXERT MECHANICAL & THERMAL STRESS ON REFRACTORIES & REDUCE THEIR LIFE (.) SO2 FROM PETCOKE BURNING SHOULD BE PREVENTED TO LEAVE THE KILN ● POSSIBLE SOLUTIONS: ● IMPROVE REFRACTORY LINING & PROVIDE BLASTERS TO CLEAN COATING ● REDUCE MATERIALS RESIDENCE TIME IN KILN ● INCREASE COAL RESIDENCE TIME IN CALCINER ● IMPROVE RAW MIX DESIGN ●ALLOW SUFFICIENT OXYGEN AT KILN INLET
  14. 14. PETCOKE AS FUEL FOR CEMENT PRODUCTION CHALLENGES IN PETCOKE BURNING: VOLATILE CYCLES ● SULPHUR-TO-ALKALI RATIO (Q) DECIDES THE TYPE OF COATING FORMED Q = (%SO3/80) / [(Na2O/62) + (K2O/94) – (Cl/71)] ● SULPHUR EXCESS, Q > 1 = HARD COATING ● ALKALI EXCESS, Q < 1 = SOFT COATING
  15. 15. PETCOKE AS FUEL FOR CEMENT PRODUCTION CHALLENGES IN PETCOKE BURNING: VOLATILE CYCLES ● TO PREVENT SO2 GAS LEAVE THE KILN, IT MUST COMBINE WITH OXIDES OF Ca, Na & K & LEAVE WITH CLINKER AS SULPAHTES (.) IN BURNING ZONE, SUFFICIENT LIQUID MUST BE FORMED FOR THESE REACTIONS TO ACCUR (.) EASE WITH WHICH THESE REACTIONS TAKE PLACE IS TERMED AS COMBINABILITY OR BURNABILITY (.) ● WITH HIGHER SULPHUR FROM FUEL, IT IS DESIRABLE TO IMPROVE BURNABILITY OR REDUCE COMBINABILITY TEMPERATURE (.) DESIRED CHANGES IN RAW MIX DESIGN COULD BE MADE IN LINE WITH THE FOLLOWING FORMULA: ● COMBINABILITY TEMPERATURE, CT, (deg C) = 436 +21(%AIR) + 10(LSF) + 3(RAW MEAL RESIDUE ON 150 MICRON) + 32(AM) - 20(%SO3) – 20(FLUORIDES) ● SUFFICIENT EXCESS O2 (> 2%) ALSO REQUIRED FOR REACTIONS TO COMPLETE: CaO + SO2 + ½O2 = CaSO4 ● SULPHATE IN CEMENT EXPRESSED AS SULPHURIC ANHYDRIDE OR SO3 = SO4 x 0.833 (.) SO3 IN CLINKER MAY BE MAINTAINED AT 1.5-2%
  16. 16. PETCOKE AS FUEL FOR CEMENT PRODUCTION CHALLENGES IN PETCOKE BURNING: VOLATILE CYCLES ●IMPROVING REFRACTORY LINING ● PROVIDE SILICON CARBIDE BASED CASTABLE REFRACTORIES AT THE KILN INLET & RISER DUCT (.) THESE REFRACTORIES FORM VITRIOUS LAYER ON THE SURFACE WITH LESS ADHERENCE PROPERTIES ● REDUCING MATERIALS RESIDENCE TIME INSIDE KILN ● REQUIRED FOR MORE FRESH RAW MATERIALS REACTING WITH SO2 FROM PETCOKE TO FORM SULPHATES (.) IT IS DONE BY INCREASING KILN SPEED ● INCREASING COAL RESIDENCE TIME IN CALCINER ● REQUIRED FOR COMPLETE COMBUSTION (.) IT IS DONE BY INCREASING CALCINER HEIGHT
  17. 17. PETCOKE AS FUEL FOR CEMENT PRODUCTION PROBLEMS FACED IN PETCOKE BURNING ● INCREASE IN NOX EMISSIONS: HIGHER CV CAUSES HIGHER “IN-FLAME” TEMPERATURES & CREATES HIGHER NOX EMISSIONS, REQUIRING NOX CONTROL TECHNOLOGIES TO STAY WITHIN REGULATORY EMISSION LIMITS ● HIGHER POWER INCREASE IN FINISH MILLS (kwh/t): LONGER BURNING ZONE (LESS VOLATILE FUEL), PRODUCES SMALLER CLINKER PARTICLES, MORE DIFFICULT TO GRIND ● HIGHER SPECIFIC HEAT CONSUMPTION (kcal/kg): HIGHER O2 LEVELS REQUIRE MORE SECONDARY AIR TO BE HEATED, INCREASING SP. HEAT CONSUMPTION ● POWER INCREASE ON PREHEATER & COOLER FANS: TO MAINTAIN ADEQUATE O2 LEVELS ● CHANGE IN KILN FEED-TO-CLINKER FACTOR: DUE TO VERY LOW ASH, MORE KILN FEED IS REQUIRED PER UNIT MASS OF CLINKER(.) KILN FEED COMPOSITION ALSO CHANGES ● ABRASIVENESS REQUIRES HIGHER MAINTENANCE ON COAL MILL ● REFRACTORY LIFE AFFECTED DUE TO COATING FORMATION
  18. 18. THANKS!!! drjdbapat.com

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