JPS638007B2 - - Google Patents

Description

[Detailed Description of the Invention] Conventionally, hydrocarbon oils that solidify at room temperature, such as Daqing crude oil, Sumatra light (Minas) crude oil, or heavy oil (pour point +20°C to +45°C) produced in China or Indonesia, have been stored in storage tanks using bottom heaters. It was impossible to store the oil in a storage tank unless it was constantly heated from the bottom to maintain its fluidity.However, it is not possible to store it in a storage tank without constantly heating it from the bottom and solidifying from the outer periphery of the oil layer. When storing and discharging the oil, a method and apparatus have been developed in which a top heater placed above the oil layer is heated to take out a portion of the molten liquid from the top of the oil layer. Furthermore, in Europe and the United States, the use of rock cavities to transport and store hydrocarbon oil has been implemented, and in Japan, a demonstration storage tank has been constructed and is at the stage of practical application.

However, in principle, it is impossible to store hydrocarbon oil that solidifies at normal temperatures with a high pour point in this rock cavity, as there is no countermeasure against it once it solidifies. It had not been put into seed.

The present invention makes it possible to store this kind of high pour point material in a rock cavity by filling water in the lower part of the rock cavity to form a water bed and storing and storing it floating on the water bed. It was a success.

The rock cavity storage tank where hydrocarbon oil is to be stored is
Various technologies are being developed, including technologies introduced from foreign countries. As a preferred embodiment of the present invention, a horizontal hole type rock excavated oil storage tank (one example of dimensions: cavity cross-sectional area height 25
m x width 15m 355.6m ² x cavity length 710m, storage capacity 252
1,000 Kl, excavation depth approximately 30 m below sea level), and its cross-sectional view (Figure 1) will be explained.

Now, a water bed 3 is formed by filling the bottom of the cavity with water in advance in a cavity excavated in the bedrock 5 that is partitioned by the underground rock storage tank wall 1 (concrete and steel lining) and the bottom plate 4. The high pour point oil 2, which is heated above the pour point and has fluidity, is initially introduced through a special nozzle installed on the horizontal surface of the water bed. When introduced into the storage tank while raising the nozzle position as the amount increases, as shown in the experimental example in Figure 2, when the receiving oil temperature is 50℃ and the water bed temperature is 22℃, the temperature change curve is almost instantaneous, as shown in the temperature change curve. In a short period of time, a thin solidified oil film is first formed at the oil-water interface, and then, while the oil-water interface maintains a temperature of almost 28.3°C, the solidified oil layer becomes thicker as time passes, and the received oil fills the storage tank cavity on the water bed surface. Fills to form 2. Thus, the underground wall 1 of the high pour point oil filled and stored in the storage tank
The contact area is cooled to a temperature that is below the pour point and is approximately equal to the rock temperature, so a solidified oil layer is formed on the contact surface, similar to the oil-water interface. As time passes, the formation of a solidified oil layer progresses slowly.

Figure 2 shows the results of this experiment, where 6 indicates the X axis (the center is the oil-water boundary), 6 indicates the Y axis (C), W indicates the water side, and O indicates the oil side. 7, 8, 9, 10 are 1.7, 36 respectively,
49, 72 Plot of temperature change from oil-water interface at each time point, 11 is solidification temperature of sample oil, 1
2 shows that the oil-water interface maintains a nearly constant value of 28.3℃.

In this case, the thermal conductivity of water in the bedrock and water bed is approximately
Compared to 0.5 to 0.45kcal/mh℃, the thermal conductivity of the solidified oil layer that forms the solidified film is much lower at 0.16kcal/mh℃ (same level as the thermal conductivity of asbestos).
As shown in the example of the oil-water interface in Figure 2, the thickness of the solidified layer increases very slowly, but heat dissipates toward the rock and water bed, forming a solidified layer around it, and increasing the internal thickness. The stored oil is surrounded by an insulating material such as asbestos, and the internal oil temperature is kept under conditions that make it difficult for the oil to drop. In this way, it is possible to store or stockpile the material stably for a long period of time within the rock cavity.

When discharging this stored storage material, by increasing the temperature of the water in the water bed, the individualized oil layer on the water bed is heated at a rate of thermal conductivity from the oil-water interface. If the temperature further rises to a fluidized state, convection occurs, rapid heat transfer occurs, and convection gradually occurs throughout the storage tank, accelerating liquefaction, and the entire storage tank, including the parts stuck to the underground walls, is heated and liquefied.

In this case, the high pour point oil introduced and stored in the storage tank as described above forms a solidified layer at the oil-water interface with the water bed and at the surface in contact with the rock cavity underground wall 1, and heat transfer is carried out by the water or water. The solidified layer slowly progresses due to the thermal conductivity and temperature difference with the bedrock, etc., and maintains a stable state. At the time of discharging, even if the bed water temperature is raised to 10 to 20 °C above the pour point of the high pour point oil being stored, the temperature will initially increase at the oil-water interface and proceed to the solidified layer due to thermal conductivity. However, local fluidization and melting progress gradually, and extremely localized small-scale convection gradually expands, so that it takes enough time for the entire contained oil, including the solidified layer, to be affected by convective heat transfer. It is necessary to allow for the required time. On the other hand, this fact indicates that it is extremely stable during storage, making it a suitable method for long-term stockpiling.

In this above water bed storage method for high pour point oil in rock cavities, the water bed water temperature is maintained at around 5°C higher than the pour point of the storage material from the beginning of the storage material delivery, and thereafter the set temperature is maintained. If the temperature is controlled, most of the contained material can be stored while retaining its fluidity, except for the part that forms a fixed layer in contact with the inner cavity underground wall, and if it is necessary to take it out, It is possible to raise the bed water temperature, rapidly cause convective heat transfer, complete liquefaction, and discharge. To explain this situation specifically, as shown in the explanatory conceptual diagram of FIG.
℃) pump 18 line heater 19 check valve 20
The temperature is always controlled at a set temperature, and the flow flows out through the outlet 16 and flows into the pipe 1.
7. Reference numeral 21 denotes a pressure regulating water tank installed above the storage tank, which is connected by a pipe branched from the pipe 17, and absorbs and adjusts internal pressure due to thermal fluctuations in the rock cavity storage tank. In this case, the water temperature in the water bed is maintained at around 18℃ throughout the year, without being affected by the surface temperature, because the underground bedrock is usually 30 meters underground, and the temperature is maintained at around 18℃ throughout the year. Both rates are
The solidified oil layer is around 0.16kcal/mh℃, and heat dissipation is extremely small, so the running cost to maintain the water bed temperature is extremely low, and it can be used as a storage method while maintaining fluidity. This method is much more economical than the method of continuously heating an above-ground tank with a bottom heater, but if the storage period such as stockpiling is long and continuous heating is required, it is necessary to use heat insulating material etc. on the inside of the bedrock or bedrock lining. It is advantageous to spray heat insulating materials to further limit the amount of heat dissipated. In addition, maintenance costs can be further reduced by selecting a storage tank location in an area that has suitable geothermal energy, using high-temperature groundwater for bed water, or utilizing geothermal heat.

This explanation was about Daqing crude oil, Sumatra light (Minas) crude oil, or heavy oil, but general hydrocarbons and petroleum products, vacuum distillation residue oil, petrochemical products, wax, etc. are lighter than water and do not dissolve in water. It can be applied to anything with a pour point higher than room temperature.

In addition, bedrock underground storage tanks are not limited to the horizontal hole type.
It can be applied to a pit-type, well-type, or existing hollow storage tank, or even an above-ground storage tank structure as long as it can maintain a water bed.

[Brief explanation of the drawing]

Figure 1 is a vertical cross-sectional view of a horizontal hole-type rock-cut oil storage tank.
Figure 2 shows a water bed temperature of 22°C, an oil temperature of 50°C, and a pour point of 35.
It is a graph of experimental results regarding the state of temperature change near the oil-water interface when sample oil at ℃ is introduced. FIG. 3 is a conceptual diagram illustrating the water bed heating system. 1...Bedrock storage tank underground wall, 2...Containment storage material,
3...water bed, 4...bottom plate, 5...ground, 6...X
Axis, 6'...Y axis, 7...1.7 hours elapsed, 8...36
Time elapsed, 9...49 hours elapsed, 10...72 hours elapsed, 11...Solidification temperature, 12...28.3℃, W...
Water side, O...Oil side, 15...Water bed water inlet, 16...
... Water bed water outlet, 17 ... Water bed water piping, 18 ... Pump, 19 ... Line heater, 20 ... Check valve, 21 ... Pressure adjustment water tank.

Claims (1)

[Scope of Claims] 1. In an underground rock cavity storage tank, a water bed is provided at the bottom, and a high pour point substance that is lighter than water and does not dissolve in water and solidifies at room temperature is fed into the storage tank and discharged onto the water bed. is a method for storing and storing high pour point substances, which is characterized by raising the temperature of the water bed to cause convection in the stored substances and discharging the liquefied substances. 2. In an underground rock cavity storage tank, a water bed is provided at the bottom, and a high pour point substance that is lighter than water and does not dissolve in water and solidifies at room temperature is introduced into the storage tank to control the water bed temperature at the bottom. 1. A method for storing and storing high pour point substances, characterized in that the stored substances are maintained at a predetermined temperature by circulating bed water.