What Are The Uses Of The Centrifuge Method Biology Essay

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Centrifuges are widely used for the purification of heavy fuel oil. The aim is to remove water contents, sediments, and minimize sodium/vanadium ratio. The properties of HFO used in this study are given in Table 7.1. The results in Table 7.2 show the characteristics of HFO after purification.

Density and viscosity were not affected. Water contents of oil were removed more then 50%.

A part of oil occurs as inorganic water-soluble salts mainly chloride and sulfates of Sodium Potassium, Magnesium and Calcium [1]. Zinc, titanium, calcium, and magnesium are also present in combination with naphthenic acid as soaps [2].

Hence removal of these metals will highly depend on the removal of water from the oil. Thus Sodium removed 66% by this method, which is supposed to be water-soluble. Calcium removed 60% it means it is present in both oil soluble napthenic acid and water-soluble salts. Most of the iron was introduced in HFO as rust of metal containers during transportation and storage. These suspended particles of iron rust are easily removed as sludge by centrifuge method. Hence, 97% removal of Iron was achieved.

Zinc and Chromium are present in the oil in very low quantity 0.2 and 0.4 ppm, detection limit of instrument is up to one decimal ±0.1, hence results of 50% removal of these metals is an approximate value.

Aluminum was removed up to 67% from oil. It is probably come with iron rust as insoluble oxides.

This method is not suitable for the removal of sulfur, which is present in organic form in oil.

Vanadium and Nickel that are present as Vanadyl Porphyrins and Nickel Porphyrins were removed only 5% and 7% respectively.

The behavior of vanadyl-vanadate (Na2O.6V2O5 and 5Na2O.12V2O5) compound produced during combustion of PDR in engines is important because they act as an oxygen transmitter (oxygen pump) and transport the oxygen to the metal surface during the processes of melting and solidifying at a temperature range of 530 - 600 °C.

Na/V-mass ratio between 0.08 and 0.45 is especially dangerous [3]. The range of the strongest corrosion corresponds to a Na/V-mass ratio of 0.15 to 0.30. Electro-chemical examinations show that sulphates cause an increase in corrosion at temperatures above 600°C, which again is considerably increased when vanadyl vanadates are present [4 and 5]. Seventeen HFO samples of different batches (properties in Table.7.3) were centrifuge and results were presented in Table.7.4. Na/V ratios were decreased from 28% to 65%; which is mainly due to decrease in sodium contents.

Table 8.1

Characteristics of Heavy Fuel Oil Batch (Sample-A)

Density @ 15 °C

0.970

Viscosity cst @ 50 °C

165

Water Contents vol.%

0.1

Ash %

0.02

Sediment by Extraction wt%

0.02

Sodium ppm

20.0

Calcium ppm

5.0

Iron ppm

3.0

Zinc ppm

0.2

Aluminum ppm

1.2

Vanadium ppm

38.5

Chromium ppm

0.4

Nickel ppm

12.8

Sulfur wt%

3.1

Table 8.2

Characteristics of Heavy Fuel Oil batch (Sample-A) after Purification

Removal %

Density

0.970

Viscosity cSt

165

Water Contents vol%

<0.05

>50%

Ash %

<0.01

>50%

Sediment by Extraction wt%

<0.01

>50%

Sodium ppm

7

66

Calcium ppm

2

60

Iron ppm

0.1

97

Zink ppm

0.1

50

Aluminum ppm

0.4

67

Vanadium ppm

36.5

5

Chromium ppm

0.2

50

Nickel ppm

11.9

7

Sulfur wt%

3.1

0

Table 8.3

Limits of Characteristic of

Heavy fuel oil batch (Samples A to Q)

Test

Method

Limits

Specific gravity @15 oC

D-1298

Max. 0.99

Viscosity

D-445

Max 180 cSt

Water contents %

D-95

Max 0.3

Sediment by Extraction

D-473

Max 0.15 %

Sulfur

D-2622

Max. 3.5 %

Sodium ppm

Max. 30 ppm

Vanadium ppm

Max. 60 ppm

Calcium ppm

Max. 10 ppm

Table 8.4

Effect of purification on Na/V Ratio

Batch

Before Purification

After Purification

Na

V

Na / V

Na

V

Na / V

% Decrease in ratio

A

20.0

38.5

0.5

7.0

36.5

0.2

65

B

15.0

30.1

0.5

6.4

28.5

0.2

57

C

5.1

25.6

0.2

2.5

25.1

0.1

51

D

4.8

20.4

0.2

2.9

20.1

0.1

40

E

4.2

19.9

0.2

2.3

19.9

0.1

45

F

5.7

21.6

0.3

3.3

21.1

0.2

42

G

3.7

20.0

0.2

1.8

19.1

0.1

51

H

16.1

24.8

0.6

6.9

24.2

0.3

57

I

19.7

35.1

0.6

11.1

34.2

0.3

44

J

25.6

34.7

0.7

10.5

31.8

0.3

59

K

25.1

38.0

0.7

8.9

37.2

0.2

65

L

14.4

41.8

0.3

9.5

41.4

0.2

34

M

25.0

40.2

0.6

13.6

38.2

0.4

46

N

17.1

34.2

0.5

11.2

34.0

0.3

35

O

19.0

30.9

0.6

9.0

29.6

0.3

53

P

11.8

36.3

0.3

8.5

37.6

0.2

28

Q

23.0

37.6

0.6

14.1

35.0

0.4

39

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