FUEL AND FUEL MANAGEMENT SYSTEM

CLASSIFICATION OF FUEL

N AT U R AL MAN MAD E(SYN T H ET IC )

SO LID

N AT U R AL MAN MAD E(SYN T H ET IC )

L IQ U ID

N AT U R AL MAN MAD E(SYN T H ET IC )

G AS

FUEL

Synthetic solid fuelCoke, Bagasse and Charcoal.

Natural liquid fuelCrude oil

Man-made liquid fuelsGasoline ( petrol ), diesel oil, alcohols, kerosene and other organic liquids

Natural gaseous fuel.Natural gas

Synthetic gaseous fuel Coke oven gas, producer gas, blast-furnace gas, water gas and refinery gas

ANALYSIS OF COAL SAMPLES: 

The boilers are designed based on

(1). Proximate analysis. (2). Ultimate analysis. (3). Gross calorific value.(4). Hard grove grindability index. (5). Fusion behavior of ash of the coal.

(1). PROXIMATE ANALYSIS 

The proximate analysis of coal means determination of the moisture content, Ash content, Volatile matter content and Fixed carbon content.  

(A). MOISTURE: • External moisture or surface moisture

Wet coal – moisture evaporate. 

• Inherent moisture

Dry coal contains some moisture which can only be removed by heating it above 100 C.

EFFECT OF MOISTURE      1 % increase in moisture will reduce gross CV by about 1 %.

Heat is also lost due to evaporation and superheating of moisture in coal during combustion. 1% moisture in the coal reduces the efficiency of boiler by 0.15%.

Ø     The wet coal reduces generation, results in increase in the secondary fuel ( fuel oil ) consumption and the auxiliary consumption.

Ø     Reduction in unloading and feeding rate.

Ø     Frequent chokage at granulators.

Ø     Due to wet coal, furnace temperature reduces. The low flue gas exit temperature can cause corrosion problems in the second pass of the boiler.

Ø     Increase in freight cost.

Ø     1 % increase in moisture in coal increases the coal consumption by about 1.23 %. Ø     1 % increase in moisture in coal will reduce useful heat value by 138 Kcal / Kg.

(B). ASH AND MINERAL MATTERS

 

The mineral matter does not contribute to the calorific value of coal. On the contrary it creates many difficulties in the efficient utilization of coal.  The mineral matter of Indian coals are calculated by using the simplified formula. Mineral matter = 1.1 A ( A = % of ash content in the coal. )

EFFECT OF ASH CONTENT

  The amount of ash content in coal can affect

      Furnace slagging rate

Fouling of heat transfer surface like Super heater, Reheater, Economiser, Air preheater.

     Amount of unburnt carbon loss increases.

     Quantity of ash to be disposed off increases , water consumption also increases.

     The size of ash handling equipments.

Frequency of soot blowing increases - increases secondary fuel consumption.

Increase in Alpha quartz content in ash increases the erosion in the boiler and gas path.

(C). VOLATILE MATTER

Volatile matter in the coal also comes into consideration while selection of coal for use in boilers.

 Volatile matter (V.M.) is that portion of the coal which gets burnt in gaseous or vapour form from the coal initially when the coal gets heated up. The main constituents of V M are Hydrogen, oxygen, CO, Methane,Hydrocarbons.

V M content in Indian coal varies from 16% to 30%.

Coal having less than 20% V M contents is usually termed as low volatile coal.

EFFECT OF VOLATILE CONTENT: 

           Low volatile coal results in poor flame stability.

  The coal having high ash contents also results in reduction of effective volatile content.

   Burning of low V.M. coal – Poor flame stability – fuel oil support required – Increase in consumption of secondary fuel oil – Chances of unit tripping on “flame failure” 

(D). FIXED CARBON: 

Fixed carbon of coal is calculated by using following formula.

Fixed Carbon = 100-(Ash% + V.M.% + Moisture%)

If carbon percentage increases, the gross CV of the coal will increase.

(2). ULTIMATE ANALYSIS

The ultimate analysis is carried out to determine the percentage of

Carbon Hydrogen

Nitrogen Sulpher Oxygen

No instrument in AECO.

Ultimate Analysis is not carried out .  

CALORIFIC VALUEThe calorific value is total heat produced when a unit mass of fuel is completely burnt with pure oxygen. The unit of CV is Kcal / Kg. 

Design of the boiler is based on gross calorific value of coal.  

In laboratory the gross CV are determined at constant volume in a Bomb calorimeter.

• NET CALORIFIC VALUE

When fuel is burnt, hydrogen combines with oxygen and gets converted into water. When water vapour is present in the flue gases, the latent heat of vaporisation is lost. Hence this quantity of heat is not available for any useful purpose.Therefore, when the calorific value of a fuel is determined, considering that water is present in a vapour form, it is said to be NET CALORIFIC VALUE OR NET HEAT VALUE OR LOWER HEATING VALUE.

• GROSS CALORIFIC VALUE

If the above vapours are condensed, the latent heat of water vapour can be made available for useful purposes. Thus if this part of heat is added to the net calorific value, GROSS CALORIFIC VALUE OR GROSS HEAT VALUE OR HIGHER HEATING VALUE is obtained.

• USEFULL HEAT VALUE = 8900 – 138 ( A + MC)It is price finalization factor. It is also used to confirm the grade of the coal.

A technologically significant grading system adopted in India is given in following table

Grade Specification

A   

HU* exceeding 6200 Kcal/Kg. 

B Hu exceeding 5600 Kcal/Kg but not exceeding 6200 Kcal/Kg.

 

C HU exceeding 4940 kcal/Kg. But not exceeding 5600

Kcal/Kg.D HU exceeding 4200 Kcal/Kg but

not exceeding 4940 Kcal/Kg.

E HU exceeding 3360 Kcal/Kg but not exceeding 4200 Kcal/Kg.

F HU exceeding 2400 Kcal/Kg but not exceeding 3360 Kcal/Kg.

G HU exceeding 1300 Kcal/Kg but not exceeding 2400 Kcal/Kg.

SPONTANIOUS COMBUSTION EFFECTING FACTORS  

Moisture, porosity, ambient temp, height of coal heap. 

PREVENTION  

Don’t pile up coal above 6 or 7 feet.

Compact by dozer.

Spray water regularly.

Don’t mix fresh and old coal.

If we look into coal map of India, We can find Eight coal fields in the country. The fields are as follows : 

1.    Raniganj, Barjora, Deoghar, Rajmahal, Sahajuri.

2.    Jharia.

3.    Giridih, Bokaro,

4.    Ramgarh, Karanpura, daltonganj, Hutar.

5.    Singarauli, Bisrampur, Lakhanpur, Korba, IB River and Talcher.

6.    Chirimiri, sohangur, Zohila river, Umaria, Pench Kanhan.

7.    Kamptee, Umrer, Wardha valleys.

8.    Tertiary coal of Assam and Lignite deposits of South Arcot, Kutch, Rajasthan and J & K state.

COAL RECEIPT IN THE A.E.CO. LTD.

INDIGENOUS COAL

IMPORTED COAL

INDIGENOUS COAL

• Different collieries• Distance from collieries. 1215 Kms to 1350

Kms.• Range of CV( 4500 to 6600 Kcal /Kg. , coal

grade and type ( STM, SLK, ROM)• Contents ( C – 45 to 55 %, VM – 20 to 25 %,

MC 1 to 10 % , Ash –25 to 30 %)• Foreign material

COST OF INDIGENOUS COAL

A. Basic cost – Ranges from Rs. 873 to Rs.1250 according to the grade.

B. Royalty per tonne of coal – gradewise – Goes to State Govn.

C. Excise duty – Rs. 3.5 per tonne of coal

D. Total of A,B,C + 4 % S.T.

E. D + Surface transportation depending on colliery + Freight + siding charges + mis. Crushing charges ( For some of collieries)

F. Total cost of coal = @ Rs. 2600 per tonne considering loss.

IMPORTED COAL

Coal from S.A. , Indonesia. Loading points – Navlakhi and Magdalla. Contents

MC – 7 to 10 % ASH – 0.8 to 1.0 % VM – 40 to 43 % FC – 46 to 49 %

GCV – 6200 to 6500 Kcal/ Kg., NCV – 5000 to 5200 Kcal / kg.). % of total receipt

BENEFITS BY USING IMPORTED COAL

Reduction in maintenance of granulators and bawl millEasy handling.Fast UnloadingLittle quantity of foreign materialReduction in ash handling timeReduction in consumption of water.Reduction in secondary fuel consumption.Reduction in bawl mill rejects.Reduction in mill and RC variater outage due to slk coal.Reduction in auxiliary consumption

RECEIPT OF COAL BY RAKE 

Rake No. of rakes per month.Quantity per rake.Consumption per day

RECEIPT OF COAL BY TRUCK  PROCESS AFTER RECEIPT OF COAL RAKE.

Receipt of rake – Dn load.Arrival time and release time Shunting work for stabling the wagonsSampling of coalShunting work for wagon unloadingWeighmentUnloading on tippler or manualShunting work of empty wagonsFormation of empty wagons rake – up load formation

DIFFERENT RAIL LINES AND THEIR USE

• Interchange line 1 to 4• ER line • Pump line• Road line• Storage line• Ash & Box line• Parking line• C1 load line and Empty line• C2 Load line and Empty line• Cross line

RAIL LINES & TRACK POINTS.

DEMURRAGE 

• Demurrage

• Free time

1 to 40 ---- 9 hrs. 45 to 58 or 60 ---- 10 hrs.

• Rates for the demurrage on coal rake.

• Demurrage = Rate * tonne of coal recd * dem hrs.

• Demurrage per rake . Rupees.

• Average demurrage hours per month.

• Reasons for demurrage --- Successive receipt of rake, S. det, Outlet constraint, Plant problem, w & s. coal, Oversized coal,

MACHINES FOR SHUNTING OPERATION

LOCOMOTIVES 

LOCOMOTIVE No.

MAKE H.P. YEAR OF MANUFAC

TURE

2 TATA 150 April ‘1963

3 TATA 150 July ‘1965

4 SAN 300 Sept. ‘1981

5 SAN 300 Sept. ‘1984

6 SAN 300 April ‘1990

7 SAN 300 May ‘1997

MACHINES FOR DOZZING THE COAL BULL DOZZERS

 

DOZER NO.

MAKE MODEL H.P. YEAR OF MANUFACT

URE

1 B E M L BD – 155

320 Nov. ‘2000

2 B E M L D 80 A – 12

180 Sept. ‘1978

3 B E M L D 80 A – 12

180 June ‘1980

4 B E M L D 80 A – 12

180 May ‘1983

5 B E M L D 80 A – 12

180 May ‘1986

6 B E M L BD – 155

320 Sept. ‘1988

7 B E M L BD – 155

320 Oct. ‘1993

8 B E M L BD – 155

320 Jan. ‘1999