JPH06126262A - Internal cleaning method for asphalt and black oil tank - Google Patents

Abstract

PURPOSE:To effectively and safely perform cleaning by using light cycle oil formed in a fluidized catalytic cracker as cleaning solution. CONSTITUTION:A after the residual oil in an asphalt tank 1 is transferred to another tank, nitrogen is sealed in to set the oxygen concentration in the asphalt tank at a specified value, for example, <=8%. And as cleaning solvent, light cycle oil 2 (hereinafter called LCO) formed in a fluidized catalytic cracker is fed about 30cm in depth from the bottom plate of the tank and circulated by a temporary pump to heat it by a heat exchanger 6 to about 60-80 deg.C and simultaneously compressed to about 5-10kg/cm<3>G and sent to a washer 4 installed in the tank 1 at a flow rate of 50-150kg/hr. In such a way, slag 3 in the tank is pulverized and dissolved in about 48hr. The washing liquid whose dissolving power has been lowered is transferred to another tank and new cleaning solvent is fed to the tank 1 and the operation is similarly repeated plural times.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an asphalt tank and a tank for black oil such as heavy oil, and more particularly to an internal cleaning method for large tanks.

[0002]

As a measure for reducing sludge in crude oil tanks and crude oil ships, there is a crude oil cleaning method in which crude oil is pumped from another crude oil tank, pressurized, and then injected through a washing machine into a tank to be cleaned. . However, regarding the cleaning of asphalt tanks and black oil tanks, as shown in Fig. 2, when opening inspections and when changing the type of oil used, after moving the residual oil, people enter the tank and set up a scaffolding for work. Then, after the residue such as sludge on the roof plate, side plate and bottom plate is directly shredded by the injection of high pressure water (water jet),
The reality is that people use tactics to clean up, such as sucking it up with a vacuum car or packing it in a bag.

[0003]

The conventional cleaning method has a problem that enormous labor, construction period and construction cost are required, and a large amount of industrial waste is generated by the cleaning work. For example, in the case of an asphalt tank with a capacity of 10,000 kl, the total number of workers is about 1,000 and the construction period is about 56.
The construction cost is about 60 million yen per day, about 250 kl of industrial waste is generated, and in the case of a black oil tank with a capacity of 29,000 kl, there are about 400 workers and the construction period is about 20 days.
The construction cost was about 20 million yen, and about 400 kl of industrial waste was generated. Further, there is a safety problem related to high-altitude work such as installation of a work scaffold inside the tank, lifting and lowering, and cleaning on the work scaffold. The present invention provides a novel, efficient and safe internal cleaning method for an asphalt / black oil tank that requires less labor, construction period, and construction cost, and that produces less industrial waste. .

[0004]

Means for Solving the Problems As a means for solving the above problems, the present inventor uses light cycle oil (hereinafter referred to as LCO) produced in a fluid catalytic cracking apparatus as a cleaning solvent. We came up with a method for cleaning the inside of an asphalt / black oil tank, which is characterized by cleaning its inside. An explanatory view thereof is shown in FIG.

The fluid catalytic cracking apparatus referred to in the present invention includes UOP type, Texaco type, flexi cracking type,
There is an orthoflow method, etc., but all of them catalytically decompose various raw material oils using a silica-alumina type or zeolite type minute spherical catalyst, there is no essential difference, It may be one. As a raw material, high boiling fractions higher than those of kerosene and light oil are widely used, but hydrogenation of atmospheric distillate distillate and vacuum distillate distillate from the viewpoints of catalyst deactivation, abnormal reaction prevention and pollution prevention. A refined oil such as a treated oil or a furfural solvent extraction treated oil, or a propane deasphalted oil is preferable. The reaction conditions include a temperature of 400 to 550 ° C. and a pressure of 1 to
About 2 kg / cm ² G is adopted.

The reaction product is fractionally distilled in a rectification column, and LCO is withdrawn as a sidestream thereof. As an example of the property, the distillation property is, for example, an initial boiling point of 150 ° C. or higher and a 50% distillation point of 25.
0 to 260 ° C, 90% distillation point 310 to 330 ° C, end point 3
It is about 50 ° C. or lower, the flash point is 60 to 75 ° C., and the aromatic content is about 60 to 85% by volume. In this way, it has a high dissolving power due to its high aromatic content, and it is a dangerous substance that falls under the Fire Service Act as a Class 4 Petroleum No. 2 oil and has a relatively high flash point and is relatively safe to handle. That means LCO
This is the reason why the solvent was selected as the cleaning solvent.

Next, the method for cleaning a tank according to the present invention is as follows.
First, after moving the residual oil of the tank to be cleaned to another tank as much as possible, an appropriate amount of LCO is put in, the LCO is pressurized by a temporary pump, etc. and sent to a washing machine installed on the roof of the tank, for example. Oil is sprayed from the washing machine and sprayed on residues such as sludge adhering to the roof plate, side plates, bottom plate, etc., crushed and dissolved, and transferred to another tank. In this case, it is preferable that the LCO is preheated, for example, in a heat exchanger or the like as needed, because the dissolving power as a solvent is improved and a further cleaning effect can be expected. A preheating temperature of about 60 to 80 ° C. is usually sufficient.

During the cleaning operation, LCO dissolves residues such as sludge, and its dissolving power gradually decreases with the passage of time. Therefore, after a certain period of time, the LCO is once transferred to another tank. After that, a new LCO is attached and the cleaning work is restarted. In this way, LC
Repeating the steps of O-filling, dissolution cleaning, and transfer several times is effective in terms of cleaning efficiency. Further, it is a preferable method to further enhance the cleaning effect by performing subsequent cleaning with warm water after cleaning with LCO.

[0009]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. Of the above-mentioned operations, especially the cleaning operation by LCO should be performed under the condition that the oxygen concentration is kept as low as possible, for example, 8% or less, by replacing the air in the tank with an inert gas such as nitrogen. It is preferable in order to secure even more safety.

[0010]

[Example 1] In the cleaning work of an asphalt tank with a capacity of 10,000 kl, the residual oil in the tank was moved to another tank by a temporary pump, and then nitrogen was sealed to keep the oxygen concentration in the tank at 8% or less. In this state, the LCO is placed on the bottom plate of the tank for about 30 cm, heated to 60-80 ° C by the heat exchanger installed at the outlet of the temporary reciprocating pump, and pressurized to 5-10 kg / cm ² G by the temporary reciprocating pump. At a flow rate of 50 to 150 kl / hr, it was sent to a washing machine installed on the tank roof, and the sludge in the tank was crushed and dissolved over 48 hours. After that, a temporary pump moved to another tank.

The sludge in the tank was reduced by repeating the steps of LCO charging, dissolution cleaning and transfer three times. After completion of the third step, industrial water was poured on the bottom plate of the tank for about 30 cm, heated and circulated, and the sludge was washed with warm water in the same manner. The total number of workers required for the above tank cleaning work was about 390, a decrease of about 610 compared to the conventional method, the construction period was about 30 days and the same was reduced by 26 days, and the construction cost was about 26,500,000 yen. The amount of industrial waste generated was about 30 kl, a decrease of 220 kl.

[0012]

[Embodiment 2] A capacity 2 is obtained in the same manner as in Embodiment 1.
Cleaning work was performed on the 9,000 kl heavy oil tank. The total number of workers required for this tank cleaning work was about 210, a reduction of about 190 compared to the conventional method, the construction period was about 10 days and the same 10 days, and the construction cost was about 10 million yen. 10 million yen decrease, and the amount of industrial waste generated is about 50 kl, 350 kl
Was reduced.

[0013]

The effects of the internal cleaning method for the asphalt / black oil tank of the present invention can be summarized as follows:
It was confirmed that a great effect was produced. No effort required. The construction period can be greatly shortened. The construction cost can be significantly reduced. Work is safe. The amount of industrial waste generated is greatly reduced.

Table 1 below shows the effects of the present invention in comparison with the conventional method for each cleaning work of an asphalt tank having a capacity of 10,000 kl and a heavy oil tank having a capacity of 29,000 kl.

[0015]

[Table 1]

[0016]

[Brief description of drawings]

FIG. 1 is an explanatory view of an internal cleaning method for an asphalt / black oil tank of the present invention.

FIG. 2 is an explanatory diagram of a tank internal cleaning method according to a conventional method.

[Explanation of symbols]

1 Cleaning Tank 2 LCO (Light Cycle Oil) 3 Sludge in Tank 4 Cleaning Machine 5 Temporary Bumper 6 Heat Exchanger 7 Oxygen Concentration Regulator 8 LCO Extension Pipe 9 Industrial Water Extension Pipe 10 Circulation Pipe and Bomb Strainer 11 Temporary Bomb Drive Steam 12 Water jet cleaning 13 Water jet car 14 Vacuum car 15 Sludge scraper 16 Scaffolding for side plate cleaning 17 Ventilation fan in tank

[0017]

[Figure 1]

[0018]

[Fig. 2]

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[Procedure amendment]

[Submission date] October 1, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is an explanatory view of an internal cleaning method for an asphalt / black oil tank of the present invention.

FIG. 2 is an explanatory diagram of a tank internal cleaning method according to a conventional method.

[Explanation of Codes] 1 Cleaning Tank 2 LCO (Light Cycle Oil) 3 Sludge in Tank 4 Cleaning Machine 5 Temporary Pump 6 Heat Exchanger 7 Oxygen Concentration Regulator 8 LCO Piping Pipe 9 Industrial Water Piping Pipe 10 Circulation Pipe and Pump Strainer 11 Temporary pump driven steam 12 Water jet cleaning 13 Water jet car 14 Vacuum car 15 Sludge scraper 16 Side plate cleaning scaffolding 17 Tank ventilation fan

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Figure 1]

[Fig. 2]

Claims (1)

[Claims] 1. An asphalt, characterized in that the inside thereof is washed by using light cycle oil produced in a fluid catalytic cracking apparatus as a washing solvent.
Internal cleaning method for black oil tank.