Ultimate Analysis

8/9/2019 Ultimate Analysis

1/11

Analysis of COAL Coal is known as fossil fuel since it is formed from fossilisedremains

of plants and animals.

Coalification takes place by two processes:

a) Streptococcus etc., convert cellulosic plant materials into peat

– Biochemical coalification. b) In the second stae, chemical reactions take place at hih temp.

! "##oC and hih pressure over a period of $#%&$#' years which

convert peat into different coal forms.

(ankin of coal:eat ! *inite ! Bituminous ! +nthracite

-$/&/-##) 0/##&%$##) '###&'/##) '0/#&'%##)

based on the calorific value 1.Cal21), volatile matter, moisture, 3, 4,

5 and S contents.


2/11


3/11

ro7imate +nalysis i) etermination of moisture content:

& By weiht loss method

= moisture ? *oss in weiht @ $##

At. of coal taken

ii) olatile


4/11

ro7imate +nalysis

>etermination of olatile matter:

& Aeiht loss method by heatin at /D2&#oC for % minutes in a muffle

furnace by puttin coal in a crucible.

*oss in weiht due to removal of volatile matter

= olatile matter ? @ $##

At. of coal sample taken

iii) +sh: & +sh is non&combustible useless material left behind durin combustion & (educes calorific value

& Causes hindrance to flow of heat reduces efficiency of heatin)

& Increases transportation, handlin and storae costs

& Burnin of coal becomes irreular >etermination of +sh:

At. of +sh formed

= +sh ? @ $##

At. of dry coal taken


5/11

ro7imate +nalysis

iv) i7ed carbon:

&(epresents the 9uantity of carbon present in coal that can be burnt

& 3ih the =Carbon, hiher will be the calorific value of the fuel

& 3elps in desinin the furnace since it is fi7ed C that burns in solid form

>etermination of i7ed Carbon:

= fi7ed carbon ? $## – =moistureD volatile matter D ash)

If we remove from the weiht of coal the moisture, volatile matter andash, the remainin weiht will be because of fi7ed Carbon alone.


6/11

;ltimate +naysis

(i) C and H in coal()

ercentae of Carbon decides the rank of the coal() 3iher = of carbon and 3, better is the 9uality of coal.

() 3iher C will ive hiher calorific value

>etermination :() + weihed 9uantity of coal $& ) is burnt in a current of dry o7yen.

() 6hey are o7idised to C4 and 3

4

C D 4 C4 and 3 D E 4 34

() 6hese aseous products are passed throuh two bulbs containin anhhydrous CaCland 143 respectively to et moisture and C4 absorbed to ive

a) CaCl D% 34 CaCl . %34 and

b) 143 D C4 1C4" D 34

() Initial weiht and final weiht of CaCl and 143 in the bulbs are measured

() Increase in weiht of CaCl ives the weiht of water formed while increase in

weiht of 143 ives the weiht of C4 formed


7/11

Carbon and 3ydroen determination in coal


8/11

;ltimate +naysis

ii) 5itroen in coal:

5itroen is a inert and non&combustible as and henceundersirable in coal.

8ood 9uality of coal should have low= of 5

>etermination of 5 in coal:

5itroen in coal is determined by 1FeldahlGs method.

$ appro7.) of powdered coal is heated with conc. 3 S4-

alon with 1S4- and CuS4- in a lon necked flask 1Feldahl

flask).

Ahen the solution becomes clear whole 5 is converted into

ammonium sulphate), e7cess 5a43 is added to liberate

ammonia.

6he ammonia thus produced is distilled over and absorbed

in a known volume $) of 52$# 3S4- std. solution.

5 D 3S4- 5aS4- D 53" D 3 4

53" D 3S4- 53-)S4-

5a43

Teflon

tube

Plastic

water

aspirator


9/11

;ltimate +naysis

+mt. of 52$# 3S4- consumed to neutralise ammonia evolved

? N/10 !1 " N/10 !# $ 0%1 (!1 & !#) 'illi e%

$ 0%1 (!1 & !#) / 1000 eui%

*t% of N $ 100

*t% of N

+ N $ 100

*t% of coal sa'ple ta,en (1 -)

$

0%1 (!1 & !#)

1000

0%1 (!1 & !#) / 1000

$

@ $- 7 $## ? #.$ (!1 & !#) 7 $.-

i%e% + N $ 0%1 (!1 " !#) 1%.


10/11

;ltimate +naysis

iii) Sulphur:

In spite of the hih calorific value of S, on combustion it produces S4 and S4"to7ic)

ases.

Sulphur is undesirable in coal when coal is to be converted into coke which will badly

affect the 9uality and properties of steel when coke is used in steel industry.

eter'ination of

+ known amount of coal is burnt in bomb calorimeter in a current of o7yen when Sets o7idised into sulphate.

6he ash from the calorimeter is e7tracted with dil 3Cl.

6he acid e7tract is treated with BaCl to precipitate BaS4-.

6he ppt. is dried, weihed. S S4-& BaS4-

At. of Sulphur ? 7 At. of BaS4- ppt.

= S in coal ?

" """

""

At. of BaS4- ppt. 7 " 7 $##

At. of coal samples taken in the bomb 7 ""


11/11

;ltimate +naysisiv) +sh:

+sh is determined usin ro7imate analysis of coal.

v) 47yen:

47yen is present in combined form with hydroen in coal and because of

this, the available free hydroen in coal is less than the actual hydroen.

3ih o7yen content indicates hih moisture content in the coal. an increase

of $= in o7yen content will reduce the calorific value of the coal by $.%=).

3ence, ood 9uality coal should have less o7yen.

>etermination of 47yen:

47yen in coal is determined by deductin C, 3, S and ash from $##.

= o7yen ? $## & = of C D 3 D 5 D S D +sh)

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Ultimate Analysis