- 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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