JPH0692583B2 - Crude oil distillation method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a crude oil distillation method, and more specifically, to a crude oil that can achieve improvement in white oil yield or a significant energy saving effect, and further both of them. It relates to a distillation method.

[Conventional technology]

The atmospheric distillation apparatus is widely used as a means for separating a crude product from crude oil.

FIG. 4 is a schematic system diagram of a conventional two-column crude oil atmospheric distillation apparatus. This apparatus comprises a front distillation column 1, a top condenser 4A for cooling the top components of the front distillation column 1, and the top condenser.
A pre-distillation tower overhead receiving tank 5A for receiving the condensate of 4A, a heating furnace 16 for heating the pre-distillation tower bottom oil, and a main distillation column for treating the pre-distillation tower bottom oil heated by the heating furnace 16. 2 and the main distillation column 2
The main distillation column overhead condenser 18 for cooling the overhead components of the main distillation column overhead condenser 18 and the main distillation column overhead condenser 19 for receiving the condensate of the main distillation column overhead condenser 18 are mainly constituted.

In the above-mentioned conventional apparatus, crude oil is passed through a line 21 for crude oil heat exchangers 9, 10 and 11 using high temperature product oil as a heat medium, and bottom oil.
The temperature is raised by 12 and crude oil heat exchangers 13 and 14 using the high temperature pump-around liquid as a heat medium, and the temperature is supplied to the pre-distillation column 1.
The crude oil is steam-distilled in the pre-distillation column 1 to obtain LPG fractions and light fractions such as soft naphtha as column top products. The bottom oil of the previous distillation column is heated in the heating furnace 16 after leaving the previous distillation column,
It is supplied to the flash zone 17 of the main distillation column 2. The overhead vapor leaving the main distillation column is condensed by a main distillation column overhead condenser 18 using water or air as a refrigerant, and the main distillation column overhead receiving tank
Pour into 19. On the other hand, heavy oil is obtained as the bottom oil of the main distillation column 2.

The refrigerant of the pre-distillation tower overhead condenser 4A is generally water or air, and the temperature of the pre-distillation tower overhead vapor condensate accumulated in the pre-distillation tower overhead receiving tank 5A is about 30 to 40 ° C. For this reason, when the operating pressure of the top distilling tower top receiving tank is low, the amount of off gas generated increases. Therefore, conventionally, the operating pressure of the pre-distillation tower overhead receiving tank 5A is usually 2.5 to 3.5 kg / cm ² G.

In the conventional crude oil atmospheric distillation apparatus, the pre-distillation column 1 is a steam distillation column (concentration column having only a concentration stage 20 and a top condenser 4A),
Alternatively, a simple flash column is used, but in either case, the degree of separation between the top product and the bottom oil is extremely poor, and a large amount of light fraction such as LPG fraction is mixed in the bottom oil of the previous distillation column.
Light fractions such as LPG fraction mixed in the bottom oil of the previous distillation column cannot be completely condensed in the main distillation column overhead condenser 18 and become offgas in the main distillation column overhead receiving tank 19. Therefore, the main distillation column top receiving tank 19 has a positive pressure, and the main distillation column internal pressure also has a positive pressure.
In general, heavy oil, which is the bottom oil of the main distillation column, contains a large amount of oil (white oil) having a higher value than heavy oil such as light oil and heavy light oil. In order to recover the white oil contained in such heavy oil, more white oil is evaporated in the main distillation tower flash zone 17, and the bottom oil of the previous distillation tower is heated in a furnace. A method of heating to a higher temperature in 16 to supply to the main distillation column and a method of lowering the operating pressure of the main distillation column flash zone are considered. But the former is
There is a limit because the required thermal energy increases, and when the supply temperature is raised, thermal decomposition of crude oil occurs, and the latter increases the off-gas generation amount in the main distillation column overhead tank 19,
There is a limit to the pressure that can be reduced.

[Problems to be Solved by the Invention]

The object of the present invention is to eliminate the above-mentioned drawbacks of the conventional method, reduce the load on the heating device between the pre-distillation column and the main distillation column, and achieve a significant energy saving, and / or the white oil yield of the entire device. It is to provide a crude oil distillation method with an improved rate.

[Means for Solving the Problems]

The first of the present invention is a method of distilling crude oil using a crude oil distillation apparatus mainly composed of a pre-distillation column and a main distillation column, wherein the top pressure of the pre-distillation column is 0.5 to 1.5 kg / cm ² G. And, by providing a reboiler and a light oil recovery stage in the pre-distillation column, the top oil of the pre-distillation column is increased, and the bottom oil of the pre-distillation column in which the light oil is reduced is supplied to the main distillation column. , While performing distillation, cooling the top vapor of the main distillation column using water or air as a refrigerant to recover condensed components, and as a result, reduce the main distillation column top pressure to -0.5 to 0 kg / cm ² G by self-reduction. It is a crude oil distillation method characterized by:

A second aspect of the present invention is that the off-gas generated from the top of the pre-distillation column in the crude oil distillation method of the first aspect is 5 to 20 kg / cm ² G.
After the pressurization, the off-gas is cooled with water or air as a refrigerant to recover a condensed component, which is a crude oil distillation method.

A third aspect of the present invention is a method for distilling crude oil using a crude oil distillation apparatus mainly composed of a pre-distillation column and a main distillation column, wherein the top pressure of the pre-distillation column is 0.5 to 1.5 kg / cm ² G. By increasing the top oil of the pre-distillation tower, and after pressurizing the off-gas generated from the top of the pre-distillation tower to 5 to 20 kg / cm ² G, cooling the off-gas using water or air as a refrigerant. , While collecting the condensed components, the bottom oil of the pre-distillation column from which the light oil has been reduced is supplied to the main distillation column to perform distillation, and the top vapor of the main distillation column is cooled with water or air as a refrigerant. , The condensed component is recovered, and as a result, the top pressure of the main distillation column is adjusted to -0.5 to 0 kg / c.
It is a crude oil distillation method characterized by self-reducing pressure to m ² G.

[Action]

In the crude oil distillation method according to claim (1), by making the pressure of the pre-distillation column lower than that of the conventional one (0.5 to 1.5 kg / cm ² G), it is easier to evaporate the oil supplied to the pre-distillation column. If there is, the light fraction mixed in the bottom oil of the pre-distillation tower is distilled out as the top oil of the pre-distillation tower, whereby the light fraction of the oil supplied from the pre-distillation tower to the main distillation column is removed to some extent. This means that the top product of the main distillation column becomes heavier, and therefore the main distillation column overhead condenser does not use a special refrigerant other than water or air to increase the cooling degree, and The pressure at the top of the main distillation column can be reduced to -0.5 to 0 kg / cm ² G without using a special decompression device. The amount of evaporation of the feedstock oil has increased, and as a result, the yield of higher value product oils (white oil) such as gas oil and heavy gas oil, which were conventionally mixed in heavy oil (main distillation column bottom oil), is increased. It becomes high and causes a so-called deep drawing effect. Further, when it is not necessary to increase the yield of white oil so much, the load on the heating device for the oil supplied from the pre-distillation column to the main distillation column can be reduced, and significant energy saving can be achieved.

In the present invention, by lowering the pressure of the pre-distillation tower, when the off-gas generated from the top-distillation tank of the pre-distillation tower increases depending on the feedstock oil, a device for pressurizing the off-gas and the pressurized off-gas are cooled. It is preferable to provide a device for recovering the condensed component in order to recover the valuable component as well as from the viewpoint of adjusting the pressure in the top distilling tower overhead tank.

Further, in the present invention, when the yield of the pre-distillation tower overhead oil is increased and the degree of separation from the pre-distillation tower overhead oil is deteriorated, it is possible to provide a reboiler and a light oil recovery stage in the pre-distillation tower. ,
In addition to being able to improve the distillation properties of the top distillation tower overhead oil,
It is also preferable from the viewpoint of preventing light oil from being mixed in the bottom oil of the pre-distillation column and reducing the pressure of the main distillation column.

〔Example〕

 Hereinafter, the present invention will be described in more detail with reference to the drawings.

FIG. 1 is a schematic system diagram of a crude oil distillation apparatus showing one embodiment of the present invention. The crude oil distillation apparatus of the present invention shown in FIG.
The former distillation column 1 is different from the conventional crude oil atmospheric distillation device shown in FIG. 4 in that it has a recovery stage 22 and a reboiler 3.

In FIG. 1, crude oil is heated via crude oil charging line 21 by crude oil heat exchangers 9, 10, 11, 12, 13, and 14 using high-temperature product oil or high-temperature pump-around liquid as a heat medium, and the pre-distillation is carried out. It is supplied to the flash zone 15 of the tower 1.

Since the overhead low-pressure receiving tank 5 of the pre-distillation tower 1 is operated at a relatively low pressure of 0.5 to 1.5 kg / cm ² G, in the pre-distillation tower flash zone 15, in addition to LPG fractions, light naphtha, etc., heavy naphtha, etc. A part of is also evaporated.

The installation of the former distillation column reboiler 3 and the recovery stage 22 enhances the ability to recover the light fractions in the bottom oil of the column, and the flash zone
Along with evaporation of heavy naphtha at 15, light fraction in bottom oil is reduced. In FIG. 1, the heat source of the reboiler 3 is heavy oil which is the bottom oil of the main distillation column, but a dedicated heating furnace may be provided as the reboiler 3.

The overhead vapor of the pre-distillation column 1 is cooled and condensed by the overhead low-pressure condenser 4 using water or air as a refrigerant, but some components may not be condensed. Since such a non-condensed gas contains a light naphtha fraction, the non-condensed gas is compressed by the compressor 6 to about 5 to 20 kg / c as shown in FIG.
Pressurized to m ² G and further cooled by a high pressure condenser 7 at the top of the pre-distillation tower using water or air as a refrigerant, a gasoline fraction,
The light naphtha fraction can be condensed and collected in the high pressure receiving tank 8 at the top of the pre-distillation tower. Generally, as the operating pressure of the pre-distillation column is lowered, the off-gas generation amount in the overhead low-pressure receiving tank 5 increases. On the other hand, the evaporation amount of crude oil in the flash zone also increases, so the yield of overhead products also increases, and the partial pressure of offgas in the overhead products becomes relatively small.
The effect of suppressing the off-gas generation is produced, and the amount of the off-gas does not extremely increase.

In such a case, it may not be necessary to install the compressor 6, the overhead high pressure condenser 7, and the overhead high pressure receiving tank 8.

The bottom oil of the previous distillation column from which the light distillate in the crude oil has been sufficiently removed is
After being heated in the heating furnace 16, it is supplied to the main distillation column 2 and, in the main distillation column flash zone 17, the fractions of heavy naphtha, kerosene, light oil, heavy light oil, etc. are evaporated. The main distillation column overhead vapor is totally condensed by the main distillation column overhead condenser 18 using water or air as a refrigerant, but since the light distillate is sufficiently removed in the previous distillation column as described above, the main distillation column column Top receiving tank 19 is 0
-0.5 kg / cm ² G It becomes a decompression state and the operating pressure of the flash zone 17 of the main distillation column can be decompressed or lowered, so that the feed oil in the flash zone 17 can be The increase in the amount of evaporation will increase the yield of white oil. The degree of pressure reduction in this case can be adjusted by changing the cooling temperature of the condensate distilled from the overhead condenser 18 of the main distillation column. Further, when it is not necessary to increase the yield of white oil so much, the load of the heating furnace 16 can be reduced as compared with the conventional case to save energy.

Below, the operation example of the crude oil atmospheric distillation apparatus of the present invention shown in FIG. 1 and the conventional crude oil atmospheric distillation apparatus shown in FIG. 4 is shown. Crude oil throughput is 50,000 barrels / day, crude oil is Minas crude oil
100%. Table 1 shows the main operating conditions for increasing the white oil yield, and Table 2 shows the product yield. Table 3 shows the main operating conditions for energy saving.

From the results in Tables 1 and 2, it is understood that according to the present invention, the white oil yield was improved in a distillation state or in a state where product properties were good without increasing the load of the heating furnace. In addition, it can be seen from Table 3 that the heating furnace load can be reduced as necessary to obtain the energy saving effect.

FIG. 3 shows an embodiment in which each means for pressurizing, cooling and condensing the off-gas of the pre-distillation tower and a reboiler and a recovery stage are provided at the bottom of the pre-distillation tower.

〔The invention's effect〕

The crude oil atmospheric distillation apparatus of the present invention comprises a recovery stage and a reboiler installed in the pre-distillation column, or / and an off-gas pressurization and coagulation device, and the pre-distillation column is operated at a low pressure.
While the light fraction such as LPG fraction is prevented from mixing into the bottom oil of the previous distillation column, the top product of the main distillation column becomes heavier, and
Generation of off-gas in the main distillation tower overhead tank is suppressed,
Allows vacuum distillation of the main distillation column. As a result, the operating pressure in the main distillation column flash zone also decreases, so the amount of flashing feedstock in the flash zone increases, and the yield of more valuable product oil such as light oil in heavy oil and heavy light oil improves. (Deep drawing effect). When deep drawing is not necessary, the crude oil supply temperature to the main distillation column can be lowered, so an energy saving effect can be obtained.

[Brief description of drawings]

FIG. 1, FIG. 2 and FIG. 3 are system diagrams showing an embodiment of a crude oil atmospheric distillation device of the present invention, and FIG. 4 is a system diagram showing an example of a conventional crude oil atmospheric distillation device. is there. 1 ... Front distillation tower, 3 ... Main distillation tower, 3 ... Front distillation tower reboiler, 4 ... Front distillation tower overhead low-pressure condenser, 4A ... Front distillation tower overhead condenser, 5 ... Front distillation tower Top low pressure receiving tank, 5A ... Front distillation tower overhead receiving tank, 6 ... Compressor, 7 ... Front distillation tower overhead high pressure condenser, 8 ... Front distillation tower overhead high pressure receiving tank, 9 ... Crude oil heat exchanger, 10 …… Crude oil heat exchanger, 11 …… Crude oil heat exchanger,
12 …… Crude oil heat exchanger, 13 …… Crude oil heat exchanger, 14 …… Crude oil heat exchanger, 15 …… Pre-distillation tower flash zone, 16 …… Heating furnace, 17 …… Main distillation tower flash zone, 18… … Main distillation column overhead condenser, 19 …… Main distillation column overhead receiving tank, 20 …… Front distillation column concentration stage, 21 …… Crude oil charging line, 22 …… Recovery stage.

Front page continuation (72) Inventor Michiro Noguchi 1464-3 Amadocho, Chiba City, Chiba Yachiyodai Heights 407

Claims (3)

[Claims] 1. A method for distilling crude oil using a crude oil distillation apparatus mainly composed of a pre-distillation column and a main distillation column,
The top pressure of the pre-distillation tower is set to 0.5 to 1.5 kg / cm ² G, and the top oil of the pre-distillation tower is increased by providing a reboiler and a light oil recovery stage in the pre-distillation tower. The reduced bottom oil of the pre-distillation column is supplied to the main distillation column to carry out distillation, and the top vapor of the main distillation column is cooled using water or air as a refrigerant to recover the condensed component, resulting in the main component Distillation column A method for distilling crude oil, characterized in that the top pressure of the distillation column is reduced to −0.5 to 0 kg / cm ² G. 2. In the crude oil distillation method according to claim 1, after pressurizing off gas generated from the top of the pre-distillation tower to 5 to 20 kg / cm ² G, the off gas is cooled with water or air as a refrigerant. A method for distilling crude oil, which comprises recovering condensed components. 3. A method for distilling crude oil using a crude oil distillation apparatus mainly composed of a pre-distillation column and a main distillation column,
By increasing the top pressure of the pre-distillation tower to 0.5 to 1.5 kg / cm ² G, the top oil of the pre-distillation tower is increased, and the off-gas generated from the top of the pre-distillation tower is 5 to 20 kg / cm ^2. After pressurizing to G, the off-gas is cooled with water or air as a refrigerant to collect condensed components, and the bottom oil of the pre-distillation column in which light oil is reduced is supplied to the main distillation column to perform distillation. , Cooling the top vapor of the main distillation column using water or air as a refrigerant, and recovering the condensed components, so that the top pressure of the main distillation column is -0.5 to 0 kg / cm ² G
A method for distilling crude oil, which comprises self-depressurizing.