- Flash Point Prediction - Petroleum Products Blending - Calculation formula and table

- Flash Point Prediction - Petroleum Products Blending - Calculation formula and table

How to predict Flash point of resultant product after blending two stocks ?  or  how to get volume required of products to get desired  blended product Flash Point ?

Many times flash point improvement is desired by blending higher flash petroleum product to lower Flash Point Product at Petroleum storage depots.

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Following table and formula can be used to predict the desirable variable figure of  volume of product or flash point.   In the table below against Flash Point Deg C some constant number "A" is listed in next column.

Flash Point   C
A

Flash Point C
A

Flash Point  C
A
20
3281

50
306

80
45
21
3004

51
285

81
43
22
2752

52
266

82
40
23
2524

53
248

83
38
24
2315

54
232

84
36
25
2126

55
216

85
34
26
1953

56
202

86
32
27
1795

57
189

87
30
28
1652

58
177

88
29
29
1520

59
165

89
27
30
1400

60
155

90
26
31
1291

61
145

91
24
32
1190

62
136

92
23
33
1098

63
127

93
22
34
1014

64
119

94
21
35
937

65
112

95
20
36
866

66
105

96
19
37
801

67
99

97
18
38
742

68
93

98
17
39
687

69
87

99
16
40
636

70
82

100
15
41
590

71
77

101
15
42
547

72
72

102
14
43
508

73
68

103
13
44
472

74
64

104
12
45
438

75
60

105
12
46
408

76
57

106
11
47
379

77
54

107
11
48
353

78
51

108
10
49
328

79
48

109
10
50
306

80
45

110
9

Formula :

Ar  * 100  =  (Vx * Ax )  +  (Vy *Ay)

A for Resultant Flash Pt * 100 = ( Volume % of  X * A for  FPx  ) + ( Volume % of Y * A for FPy )

Where  FPr = resultant flash point of blend in centigrade
            Vx =  Volume percentage of X component
            Vy = Volume percentage of  Y component
             Ax =  Constant A from table corresponding to flash point of X
            Ay =  Constant A from table corresponding to flash point of Y
            Ar  = Constant A from table corresponding to flash point of R

The above formula is clear from the following examples:

Ex 1:     Flash Point of Blend 

                Component X,  Flash Pt =30 C,   vol=50 %,   From table A for 30 C FP = 1400

                Component Y,  Flash Pt =50 C,   vol=50 %,   From table A for 50 C FP = 306

Then  from equation   Ar* 100 = (50 * 1400)  + (50 * 306)

              Solving         Ar  =  853

               From the table,  nearest  Resultant Flash Point is 36 at Constant Ar of 853.  



Ex 2:       Flash Point of Blend 

                  Component X,  Flash Pt =25 C,   vol=10 %,   From table A for 25 C FP = 2126

                  Component Y,  Flash Pt =45 C,   vol=90 %,   From table A for 45 C FP = 438

Then  from equation   Ar* 100 = (10 * 2126)  + (90 * 438)

              Solving         Ar  =  606

               From the table,  nearest  Resultant Flash Point is 40 at Constant Ar of 606.  
                                                                                                                                                                                                                                                                                                                                                                                                     

Ex 3:       Flash Point of Blending Volumes percentages  to get  38 deg C

              Let Vx = Volume % of X component,   therefore Vy = 100 – Vx.

                  Component X,  Flash Pt =28 C,   vol=Vx %,   From table A for 25 C FP = 2126

                  Component Y,  Flash Pt =?  C,   vol=(100-Vx)  %,  From table A for 38 C FP = 742

Then  from equation   742 * 100 = (Vx * 2126)  + (100-Vx) * 438)
                                                     =  2126 Vx - 438 Vx + 43800


              Solving         Vx  =  18 %,   and therefore  Vy = 82 %
               .  




Notes :  Above calculations predict nearly accurate Flash Point of blended product, however, usual precautions are must for margin in flash point to take care non-homogeneity of mixture and layering in petroleum product tank.

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Comments

Ravi Gajera said…
Sir, its very useful information regarding flash point of SKO.
My question is, is this table or formula also helpful incase of HDD or LSHF HSD inplace pf SKO?
Anonymous said…
Sir, how the constant value A derived?
Vijayakumar K said…
Sir, How this formula has been arrived at ? Will it not behave simple weighted average formula ?
R J Patel said…
Thanks Dr Ravi Gajera for your comments.

Yes, this method is useful for any other product like diesel fuels, Aviation Jet Fuels etc.

Significant contamination with lighter product may bring a bit lower value of blend.

R J Patel said…
Regarding Mr. anonymous comment - will appreciate - Please care to give identity and email so that detail reply can be made.

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