Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Patent
1987-07-08
1989-06-27
Nelms, David C.
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
356436, G01N 1506
Patent
active
048432474
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a method of rapid determination of asphaltene content in heavy hydrocarbon oils, such as long residue, short residue, hydrocracked oil, thermally cracked oil, shale oil, tar sand oil, etc., and to a device for automatically carrying out such determination.
BACKGROUND ART
An asphaltene content in heavy hydrocarbon oils is not only an indication of combustibility and storage stability of heavy hydrocarbon oils but also an important factor greatly influencing catalytic activity in a direct disulfurization process. Therefore, it is required to carry out determination of asphaltene content in heavy hydrocarbon oils rapidly and precisely from consideration of product control and process control.
Determination of asphaltene content has been commonly carried out based on a method of The Institute of Petroleum (IP 143, hereinafter referred to as IP method). IP method comprises dissolving a sample in a prescribed amount of warm n-heptane, filtering the resulting mixture using a filter paper, washing an insoluble matter collected by filtration with heptane at reflux in a Soxhlet's extractor, extracting the insoluble matter with toluene in the extractor, and determining the extracted soluble matter. However, since the IP method involves complicated operations and requires much time as long as 9 hours for analysis, it has been partly replaced by a method of Universal Oil Product Co. (UOP 614/80, hereinafter referred to as UOP method), in which a sample dissolved in a prescribed amount of warm n-heptane is filtered through a membrance filter and the insoluble matter collected on the filter is determined as an asphaltene content. The UOP method, however, still requires about 4 hours for analysis, and the measured values do not agree with those obtained by IP method. Accordingly, it has been demanded to develop a simple and rapid method of asphaltene determination which gives measured values in good agreement with IP values.
Methods of rapid determination of asphaltene content so far proposed include (1) Ono method (Tastuo Ono, J. of Japan Petrol. Inst., Vol. 14, No. 9, 504 (1971)), (2) absorptiometric methods (Tsutomu Kaibara et al., J. of Japan Petrol. Inst., Vol. 23, No. 3, 178 (1980)), and (3) hydrogen flame ionization detection thin-layer chromatographic methods (FID-TLC) (Marc-Andre Poirier et al., J. of Chromatographic Science, Vol. 21, No. 7,331 (1983) and Yojiro Yamamotlo et al., J. of Japan Petrol. Inst., Vol. 27, No. 3,269 (1984)).
The Ono method comprises the same procedures as IP method except for omitting the toluene extraction, and the time required for analysis and measured values are substantially equal to those of the UOP method.
The hydrogen flame ionization detection thin-layer chromatographic method by Yamamoto et al. comprises spotting a sample solution on a silica gel thin layer rod, developing the sample with a solvent, e.g., toluene, to separate asphaltene, and determining the asphaltene content by means of a flame ionization detector. Although this method succeeded to furnish measured values in correlation with IP values and to reduce the time required for analysis to 30 to 60 minutes per 10 samples, it has disadvantages in that an analyst should always scan the system throughout measurement and that analysis precision greatly depends on development conditions, resulting in poor reproducibility.
The absorptiometric method by Kaibara et al. comprises dissolving a sample in n-heptane, measuring absorbance of the solution at a wavelength of 700 nm by means of a spectrophotometer, further measuring absorbance of a filtrate obtained by filtration of the solution at a wavelength of 700 nm, and obtaining an asphaltene concentration from a difference in absorbance of the solution between before and after the filtration. According to this method, the time required for analysis is reduced to about 30 minutes. However, the operation of filtration is complicated, and the measured values, though correlating with IP values, has a coefficient of correlation of 0.979
REFERENCES:
patent: 2761067 (1956-08-01), Troy, Jr.
patent: 3790156 (1975-06-01), Heigl et al.
patent: 4136959 (1979-01-01), Honkawa et al.
patent: 4544840 (1985-10-01), Keller
Tsuji Hiroshi
Yamazoe Seigo
Cosmo Oil Co. Ltd.
Nelms David C.
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