Mineral oils: processes and products – Refining – Sulfur removal
Reexamination Certificate
1996-09-23
2001-12-11
Preisch, Nadine (Department: 1764)
Mineral oils: processes and products
Refining
Sulfur removal
C208S213000, C208S217000, C208S25100H, C208S253000, C208S25100H
Reexamination Certificate
active
06328880
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an improved process for the hydrotreatment of a hydrocarbon oil and a fuel oil composition produced thereby. More particularly, it pertains to an economically advantageous process capable of stably efficiently producing kerosene, gas oil and the like that have favorable color tone and high quality by treating a hydrocarbon oil such as crude oil, crude oil from which naphtha fraction is removed or the like through a step in which a specific catalyst is employed or the service life of a catalyst can be prolonged readily and inexpensively, a step capable of prolonging the continuous operation period of treating equipment, a step capable of simplifying the oil refining equipment, or the like step; and to a fuel oil composition such as kerosene, gas oil or the like which is obtained by this process for the hydrotreatment, is minimized in sulfur content and has favorable color tone.
BACKGROUND ART
As a process for the refining treatment of crude oil, there has heretofore been adopted the process which comprises the steps of atmospherically distillating crude oil to separate each of the fractions and thereafter desulfurizing the respective fractions thus separated. The above-mentioned process, however, is not necessarily satisfactory, since it involves the problems that a large number of refining apparatuses are required, the steps are intricate and troublesome, repeated cooling and heating of the petroleum products lower the energy efficiency and the like. In view of the above, a novel system of petroleum refining is eagerly desired.
From such viewpoint, an attempt has recently been made to collectively treat crude oil from which naphtha fraction is removed. There have been proposed, for example, (1) a process comprising the steps of distilling away naphtha fraction in crude oil; then collectively hydrodesulfurizing the residual petroleum free from naphtha fraction; and subsequently distilling the hydrodesulfurized petroleum to separate it into respective petroleum products (refer to Japanese Patent Application Laid-Open No. 294,390/1991), (2) a process comprising the steps of distilling away naphtha fraction in crude oil; then collectively hydrodesulfurizing the residual petroleum free from naphtha fraction; subsequently separating the hydrodesulfurized petroleum in a high pressure separating vessel into light fraction and heavy fraction; and then hydrorefining the light fraction thus obtained (refer to Japanese Patent Application Laid-Open No. 224,890/1992), (3) a process comprising the steps of distilling away naphtha fraction in crude oil; then collectively hydrodesulfurizing the residual petroleum free from naphtha fraction; subsequently separating the hydrodesulfurized petroleum in a high pressure separating vessel into light fraction and heavy fraction; catalytically cracking the heavy fraction thus obtained at around 500° C. in nitrogen atmosphere under around atmospheric pressure to obtain gasoline and light cracked oil (LCO); and then hydrorefining the LCO thus obtained and the light fraction which has been separated under high pressure (refer to Japanese Patent Application Laid-Open No. 224,892/1992), (4) a process comprising the steps of subjecting crude oil to collective treatment and atmospheric distillation; then subjecting the residual oil thus obtained to fluidized catalytic cracking or hydrocracking; and adjusting the product yields (refer to U.S. Pat. No. 3,617,501), (5) a process in which proper operating conditions having high economical efficiency are provided in a collective hydrotreatment of crude oil highly liable to metallic contamination by means of a moving-bed type reactor capable of continuously replacing a catalyst, in particular, a process in which continuous operation period of the production process is prolonged as compared with conventional processes and at the same time, the content of nitrogen, a metal or asphaltene in the residual oil is decreased by the combination of contaminant removal using the first-stage countercurrent moving-bed type reactor and hydroreforming using the second-stage fixed-bed type reactor, and the like processes.
However, with regard to the above-mentioned process (1), the use of a conventional desulfurization catalyst makes it impossible to produce kerosene and gas oil fractions that are stabilized in quality, and besides to exhibit satisfactory effect on the increased production of clear oils. Specifically, in the case where a conventional fixed-bed type reactor is used in the process (1), the continuous operation period of the production process is not satisfactory, and besides the product properties of each fraction, for example, nitrogen contents and color tones of kerosene and gas oil, the smoke point of kerosene, or the content of nitrogen, a metal or asphalten in the residual oil have been inferior to the properties of the products obtained by a conventional refining process. With respect to the aforestated process (2), although the properties of the kerosene and gas oil are improved, the smoke point of the kerosene is not fully satisfactory depending on the purpose of use, the usable crude oil is limited depending upon the demand constitution, and besides there is caused such a problem that the treating equipment is complicated because of the practice of desulfurizing treatment, followed by the hydrorefining, thereby inevitably increasing the equipment cost and running cost. As to the above-mentioned process (3), the production of gasoline is increased along with the production of LCO having the boiling point range corresponding to that of kerosene and gas oil, but the LCO thus obtained is extremely high in aromaticity and is remarkably low in the smoke point of the kerosene fraction and in the cetane value of the gas oil fraction. In order to achieve satisfactory smoke point or cetane value by hydrogenating such LCO, it is necessary to provide a high temperature and pressure unit withstanding a high degree of severeness and also to reboost the LCO up to the reaction pressure. Accordingly there has not yet been attained economical efficiency satisfactory in both fixed cost and variable cost. In regard to the process (4), the intermediate fraction obtained by fluidized catalytic cracking is extremely poor in its quality, including for example, the hue of gas oil or kerosene, the smoke point of kerosene, the cetane index of gas oil, etc. On the other hand, it is imperative in the hydrocracking, that the temperature and pressure which have once been lowered in the atmospheric distillation should be raised again to a high temperature and pressure, that is, to 300 to 450° C. and 100 to 200 kg/cm
2
, and therefore, this process itself is not necessarily satisfactory from the viewpoints of energy efficiency and economical efficiency. Regarding the above-described process (5), although the residual oil is improved in its quality by carrying out collective desulfurizing treatment of crude oil or crude oil from which naphtha fraction is removed, by the use of a conventional desulfurization catalyst, there is caused such a problem that the kerosene and gas oil components are unsatisfactory in the quality, for example, smoke point and hue stability. Thus it has been clarified that the single use of the moving-bed type reactor is devoid of practicability for the collective treatment. Moreover, since the moving-bed type reactor must be applied to crude oil highly contaminated with metals (for example, not less than 150 ppm), that is, a heavy fraction from the economical point of view, there is a problem that the usable crude oil is restricted.
The actual circumstance at the present time of the conventional collective treatment process for crude oil from which naphtha fraction is removed is that the above process is not yet brought to practical application owing to the difficulty in producing kerosene and gas oil fractions stabilized in qualities, insufficiency in continuous operation period of the production process and expensiveness in equipment cost and running cost.
On the o
Iwamoto Ryuichiro
Konishi Toshihisa
Matsuda Satoshi
Nozaki Takao
Ohta Nobuyuki
Idemitsu Kosan Co. Ltd.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Preisch Nadine
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