T H E JOURNAL OF INDUSTRIAL A N D ENGINEERING CHEMISTRY
966
Vol. 14, No. 10
Coke Residue Test for Creosote Oils' By Charles S. Reeve and Frank W. Yeager RESEARCH DEPARTMENT, THEBARRETT Co., EDCEWATER, N. J .
URING the past year the authors' attention was called to rather marked discrepancies in the results of this test,2 not only in different laboratories but with the same operator when testing oils especially prepared and distributed for comparative work. The possible variations in the test were first shown by experiments on two samples of oils distributed to four laboratories with instructions to follow the method outlined. The results of these experiments are given in Table I.
This wide variation in results led to a consideration of the factors that might be responsible. Our conclusions may be summarized as follows:
D
(1) SHAPEOF Bum-While the specifications for a bulb are narrow as to shape and dimensions, we have found it practically impossible to obtain the desired uniformity, and it is usually necessary to select from a large lot those which most closely approximate the specification. (2) CHARACTER OF GLASS-Many of the bulbs on the market are made of a soft glass, which either prevents the proper application of the full flame heat, or through fusion and consequent shrinkage of the glass walls causes a change in the relation of volume of oil to bulb capacity. (3) RATEOF DISTILLATION-It is difficult to keep this constant on account of the small vapor space above the oil and because of the frequent necessity of conducting the distillation intermittently in order to avoid spurting, particularly when the oil contains traces of water.
TABLE I SAMPLE 1
c -
Test 1
2 3 4 5 6
A 8.0 7.3 8.00 8.0
... ...
Av. 7.8
B 10.8 11.1 7.8 9.2
... ...
9.7
.
C 9.2 10.5 10.3 9.9 9.9
11.8 12.3 10.1 9.9
...
,.. ...
10.0
11.0
D
-----SAMPLE --2 A 4.2 4.0 4.1 4.4 4.2 4.4 4.2
B 7.6 7.2 6.8
...
... ...
7.2
C 6.3 6.1 6.4 5.8 5.2
D 7.3 7.8 7.3 7.3
...
... ...
6.0
7.4
Efforts were made to minimize these effects by purchasing a few special hard-glass bulbs that came very near the specifications, but in no case was there any material increase in the ability to obtain better check results. These results are included in Table 11. This investigation led to the conclusion that some method should be devised that would eliminate coking in glass, but a t the same time give results more nearly constant and substantially in accord with those heretofore obtained in the bulb, and so avoid as far as possible any conflict with existing oil specifications. This involved a distillation with subsequent coking of the residue and it was decided to associate the coke test with the retort distillation as given in American Society Testing Materials D-38-18. The following procedure was therefore devised: (1) The oil was subjected to retort distillation; (2) the residue above 355" C. was subjected to the test for fixed carbon (A. 8. T. M. D-22-16) using a Bunsen burner; (3) the percentage [of fixed carbon (coke) was calculated back to the original sample of oil. In trying out the method, each of four oil samples was tested by two operators. Table I11 gives the distillation tests, percentage of coke on residue, and calculated percentage of coke on the oil.
These result,s show a remarkable dissimilarity between the different laboratories on the same oils, and a general failure to get close checks even in the same laboratory. The variations of the tests in the individual laboratories expressed as maximum per cent variation from the average are: LABORATORY
Sample 2 Per cent
Sample I Per cent
A B C D
9 20 8 12
5 6 13 5
The variation between laboratories on the same oil is 19 per cent for Sample 1, and 32 per cent for Sample 2. Inasmuch as this test is used as a basis for estimating the amount of refined tar blended in a finished creosote, and as the oils are often required to fall within a specified limit in this respect, it is readily seen from these results that the test is not satisfactory. 1 8
Received May 4, 1922. Am, Soc. Testing Materials, Standard D-38-18.
-
TABLE I I ~ U M MOF A TESTS R Y COMPARING COKE-BULB AND RESIDUE-CRUCIBLE TESTSOP CREOSOTEOIL COKE -31-----41-F -5 -1 --61 2 1 2 1 2 1
Sample of oil Ouerator Coke-bulb tests, per.cent variation Retort distillation, per cent distillate: 0-170° C.
0-210 0-235 0-270 0-315 0-355
.
Residue Loss
.... 0.0
3.3 27.6 48.0 59.6 70.3 29.0 0.7 1
Residue-Crucible Test
Av. per cent coke in oil Per cent variation Type of crucible Range of per cent coke by bulb test Pet:cent coke by special hard bulbs I-Per 11-Per
9.4
&lo.
28.1 27.5 27.8 28.0
cent fixed carbon in residue. cent coke, whole oil basis.
I1 8.1 8.0 8.1 8.1 8.1 *l.
0.0 3.0 26.2 48.6 60.1 70.5 28.9 0.6 I 27.8 27.8 28.0
..
(a)
I1 8.0 8.0 8.1 8:O *l.
5.7
*.
*lo.
0.0 3.2 32.2 56.0 68.2 78.6 20.2 1.2
0.0 4.7 34.6 57.3 69.4 79.5 20.4 0.1 I1 I 5.2 25.0 5.2 25.3 5.2 25.3 6.2 5.2 0.
I
25.9 25.9 25.8 26.8
(a)
8.5 to 10.2
..
(a)
5.4 t o 6.3
3.2
0.1 0.4 4.6 22.0 42.5 70.7 28.7 0.6
I1 5.1 5.2 5.2 5.,.2
=t2. (a)
I 9.4 9.2
.. ..
0.9 *27.
3.7 *lo.
&lo.
2 . I
0.0 0.0 0.2 0.5 2.4 1.8 20.1 15.3 42.0 42 3 73.6 89:1 25.3 30.7 0.2 1.1 I1 I I1 I I1 2.7 9.2 2.8 2.7. 0.7 2.7 9.2 2.8 2.7 0.7 9.2 2.8 2.,.7 2.,'s o.,.7
..
0.
.. ..
..
0.
(b)
(a)
2.9 t o 3.6
..
0
b)
..
a-10 cc. capsule type of crucible. b 2 0 cc. regular form of crucible.
Ir 0.P 0.6 0.5
i):6 k17.
0:7 t o 1.0
5.0-6.2 Av. 5.6 1 Refined t a r solutions. 8 Distillate oil.
0.0 0.4 2.3 16.4 40.9 73.9 25.7 0.4 I 2.9 2.5 2.1
(a>
