JPS60118202A - Distillation tower - Google Patents

Abstract

PURPOSE:To keep a distillation temp. high by reducing the stay time of crude oil while raising the yield of an intermediate fraction, in a distillation tower of which the inner diameter is reduced in the bottom part thereof, by extending a tower bottom nozzle into the tower. CONSTITUTION:To the bottom of a distillation tower having a height H corresponding to 1-20% of the tower height, a tower bottom nozzle having a height (h) corresponding to 1-25% of H. The heavy oil component of crude oil is withdrawn from the tower bottom nozzle to reduce the stay time thereof in the tower bottom part.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a distillation column, and more particularly to a distillation column in which the structure of the bottom of the column is improved to shorten the residence time.

Since the oil crisis, the production and demand for petroleum products have been decreasing due to the spread of energy conservation, the shift to alternative energy, and the economic downturn.In particular, heavy oil has seen a decline in the industry's shift to alternative energy such as coal. This is expected to continue for the time being, and demand is expected to decline in the future.

Therefore, when producing various petroleum products from crude oil by distillation, it is necessary to consider the demand for the products, and it is desirable to increase the yield of middle distillates such as white oil. -I went back.

In order to increase the yield of middle distillates by distilling crude oil,
It is necessary to raise the temperature at the bottom of the distillation column as high as possible, but the higher the temperature, the more likely carbonaceous matter will be generated. Furthermore, in order to minimize the generation of carbon due to decomposition of heavy oil extracted from the tower bottom nozzle, it is necessary to shorten the residence time of crude oil at the tower bottom.

Although there are various types of distillation columns, it can be said that a type of distillation column in which the inner diameter of the column bottom is smaller than that of the other portions satisfies the above-mentioned requirements to a certain degree. However, it cannot meet the demand for further improvement in the yield of middle distillates.

In view of these circumstances, the present inventors have made repeated studies to improve the structure of the distillation column and the structure of the bottom of the sifting column, and as a result, have arrived at the present invention.

The present invention provides a distillation column of a type in which the inner diameter of the bottom part is smaller than that of other parts, and is characterized in that the bottom nozzle is extended into the column.

In the present invention, distillation columns used for any of atmospheric distillation, vacuum distillation, and pressurized distillation are targeted, but distillation columns for atmospheric distillation and vacuum distillation are particularly suitable.

Figure 1 is an explanatory diagram of a distillation column according to the present invention. A distillation column with a narrowed inner diameter at the bottom as shown in the figure has a relatively high temperature at the bottom when distilling crude oil. can be maintained. Therefore, we investigated other conditions necessary to improve the yield of middle distillates, namely shortening the residence time at the bottom of the column. It was found that the objective could be achieved by extending the period.

The bottom of the distillation column (the part where the inner diameter is narrowed in the figure) has a height of 01 to 20%, preferably 10 to 1%, from the bottom of the column.
5% of the height, but when the height of this tower bottom is H, the length of the pipe extending into the tower is 1 to 25% of ■, preferably 5 to 10%. Should. Further, the thickness of the pipe may be the same as or larger than that of the outlet nozzle.

To renovate the inside of an existing distillation column as described above, work can be done inside the column by entering and exiting through the manhole (or handhole in the case of small distillation columns), and the pipe for the nozzle must be cut to the specified length. You just need to extend it.

The distillation column of the present invention requires only slight improvements to the existing distillation column, and the initial work is simple.

According to the distillation column of the present invention, the distillation temperature can be maintained high during distillation of crude oil, and the residence time of crude oil at the bottom of the column can be shortened. Therefore, the yield of middle distillates such as white oil is improved, and the heavy oil extracted from the bottom of the column has a low carbon content. Therefore, when this heavy oil is directly supplied as a raw material for desulfurization or the like, the effect of improving reaction efficiency and decomposition efficiency can be obtained.

Next, an example of use of the distillation column of the present invention will be shown.

Usage example Raw material oil (seed disease: heavy oil, high sulfur crude oil, production area: Middle East, specific gravity (15/4°C,); 0.875. Sulfur content; 2.
58 wt%, pour point: -29.8°C), and a distillation column with a column height of 55 Jjm and an inner diameter of 4.1 m (however, the inner diameter of the bottom of the column: 3.2ty+, the height H: 5.7 m, and the pipe length. Sah
Distillation was carried out under conditions of an oil flow rate of 9500 kt/day and a flash zone pressure of 0-64 k2/cd G. Table 1 shows the yield of heavy gas oil and atmospheric residual oil at this time.

Table 1 Heavy gas oil yield (%) 15 10 Normal pressure residual oil yield (%) 55 40 Flash yJ#! IJ: (C) '574! +6
0* Existing distillation column

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a distillation column according to the present invention. Patent applicant: Okinawa Oil Refining Co., Ltd. Figure 1

Claims (1)

[Claims] A distillation column of a type in which the inner diameter of the bottom part is smaller than that of other parts, and characterized in that the bottom nozzle is extended into the column◇