JPS6025515A - Apparatus for removing component dissolved in oil - Google Patents

Abstract

PURPOSE:To enhance the removal efficiency of a dissolved component by promoting degassing, by separately supplying unpurified oil and recycle oil to a packing layer. CONSTITUTION:An oil sprayer 8b is provided in a vacuum degassing tank 7 other than an oil sprayer 8a for spraying unpurified oil 18 and the recycle oil 17 taken out from the vacuum degassing tank 7 is sprayed from the oil sprayer 8b while inert gas 22 is leaked into the vacuum degassing tank 7 through a leak value 23. Unpurified oil is sprayed into a vacuum atmosphere under atmospheric pressure to perform degassing in a boiling state and gas other than the gas component dissolved in oil is leaked to the vacuum degassing tank to lower the partial pressure of a gaseous phase dissolved component and gas separated from oil is carried out of the degassing tank by the leaked gas.

Description

[Detailed description of the invention] Hydrogen, methane, ethane, propane, butane.

In a silk pressing machine that compresses hydrocarbon residues such as pentane, hexane, henotane, etc. and H2S contained as impurities in these, the sol oil used for shaft sealing etc. contains Jjk, min. of the gas to be compressed, etc. , Since moisture in the air dissolves, the physical properties of the seal oil are maintained, and explosion-proof safety is maintained.

From this point of view, oil equipment requires countermeasures. In particular, the compressed gas at the source of the gas well is 1 (quality components include pentane, hexane to undesonone).

It often contains components up to dodecane as well as high concentrations of H2S. Therefore, after passing through the seal portion, these components are dissolved in large quantities in the seal oil, and unless these dissolved components are removed, the seal oil cannot be reused as a seal oil.

If hydrocarbons or H2S remain in the seal oil, the flash of the seal oil will decrease, increasing the risk of fire or explosion when storing the seal oil in a tank, and will also damage the tank, piping, and seal ring. Corrosion such as this is also a problem.

Therefore, in general, it is necessary to remove dissolved components from seal oil in preparation for use, and the known methods for removing this include ■ Method by heating ■ Method by bubbling with inert gas such as air, N, CO2, etc. ■ Method by vacuum ing.

Among these, a conventional example of an apparatus for removing dissolved components in oil using a vacuum method will be described.

In FIG. 1, oil 1 to be purified is supplied through a valve 2, and after first removing sludge with a strainer 3,
f via feed pump f4 and U a ft controller 5
After heating with an electric heater 6, the oil is sprayed into the space from the top of the vacuum degassing tank 7 with an oil sprayer 8. The vacuum degassing tank 7 is connected to the empty drawing line 9
Since it is constantly evacuated through a vacuum bomb 7°10 and released into the atmosphere as a spray, the vacuum atmosphere is strange.
It is formed. Therefore, the oil sprayed into the vacuum degassing tank 2 becomes a large number of droplets or liquid columns, increasing the interfacial area, and as a result, degassing progresses due to interfacial forces. Oil 12 in the reservoir purified in this way
is taken out from a part of the discharge flow of the pump 13, and becomes the purified oil 16 at a predetermined flow rate through the filter 14 and the flow rate wi, l1 (i'i meter 15. However, in a one-time spray, Since a sufficient deaeration effect or purification effect cannot be expected, the unpurified oil 18 immediately before entering the vacuum deaeration tank is taken out from the vacuum deaeration tank 2 via the storage tank oil 12 depletion pump 13 and recycled oil 17. The current practice is to merge the water with the water and spray it again.

Next, in the conventional example shown in FIG. 2, a packed bed 20 is provided below the oil sprayer 8 in the vacuum degassing tank 7.

When recycled oil 17 and unpurified oil 18 immediately before entering the vacuum degassing tank are combined, the mass transfer rate decreases as shown below.

First, the degassing rate is expressed by the following formula.

NB =V(KLa(xi-xt”) −・・−−<
Here, N: Degassing rate (lcg-+nolAr) ■: Degassing chamber effective degassing volume (m8) K: t, a: Capacity coefficient ()'l? mol/rrL”
Hr °mole fraction) x Dissolved gas concentration in oil (mole fraction)

In equation (1), unpurified oil 18 is sprayed after merging with recycled oil 17, and (K La )
Since i is the capacity coefficient of component i under vacuum, 10-
It is small, on the order of 2 to 10-1 [+Cg-mol//'rrL8Hr], and therefore the degassing rate is also small. Therefore, in order to obtain a predetermined removal efficiency, a considerably large packed bed 20 is required.
In the illustrated apparatus, the only gas present in the vacuum degassing tank 7 is the gas dissolved in the oil 1 to be purified. Therefore, the gas dissolved in the oil cannot be removed below the thermodynamic equilibrium composition determined by the operating temperature and pressure of the vacuum degassing tank. This will be explained theoretically below.

The degree of dissolved gas in oil xi* in equilibrium with the gas phase is expressed by the following equation.

X, umbrella = yt/Ki - (2) where, y: gas temperature in the gas phase (mole fraction) K: vapor-liquid equilibrium relationship In the thermodynamic equilibrium state, Since the degassing rate is zero, by setting Ni20 in equation (1) and considering equation (2), 3' i = Ki ” i ”””””” (3) That is, equation (3) represents the vapor-liquid equilibrium relationship.

Therefore, if we include the total pressure P on both sides of equation (3), Pyl will be the gas phase partial pressure Pi of component i.If we take the sum of the partial pressures for all components, then as can be seen from equation (4), If the sum of the partial pressures of the gas phase in equilibrium with the liquid phase, that is, the total pressure, becomes equal to the operating pressure of the vacuum deaeration tank 7, no further deaeration will proceed. For simplicity, consider an example in which only n-hexane is dissolved in turbine oil, and set the operating conditions of the vacuum degassing tank to 70'G and 1.5
Let's consider the limit of deaeration of the platform as mmHg abg. The vapor-liquid equilibrium constant of n-hexane at 70°C and 1.5 mmHg abs is 2507, and since the gas phase is almost exclusively n-hexane, it is 21. (l. Therefore, under equilibrium, i.e. 70°C', 1.5 mmHg abs
(Under D'm conditions, n-hexane in oil cannot be reduced to less than 0.2 molar concentration.

With conventional equipment, if it is necessary to further reduce the dissolved gas concentration in the oil, there is no choice but to raise the operating temperature or lower the operating pressure, but in order to prevent oil deterioration, the temperature must be around 90°C.
The limit is 100°C, and if the pressure f is lowered by one order of magnitude, the residual gas level can be expected to be reduced to 1/10, but on the other hand, there are problems such as the need for a vacuum pump with 10 times the exhaust capacity. .

The present invention was made to solve these problems, and its purpose is to supply unpurified oil and cycle oil separately to a packed bed, that is, to transfer unpurified oil from normal pressure to vacuum. Dissolution in the gas phase can be prevented by spraying on the oil to cause deaeration in a turbulent state, increasing the deaeration rate, and leaking gases other than the gas components dissolved in the oil into the vacuum deaeration tank. Dissolved component removal device 6 in oil that can reduce the partial pressure of the components and at the same time allow the leaked gas to carry away the degassing outside the degassing tank, thereby promoting deaeration and increasing the efficiency of removing dissolved components. Our goal is to provide the following.

An embodiment of the present invention will be described below with reference to FIG.

The red coating for removing dissolved components in oil shown in FIG. 3 differs from the conventional apparatus shown in FIG. 2 in the following points. That is, an oil sprayer 8b separate from the oil sprayer 8a that sprays unpurified oil 18 is provided in the vacuum degassing tank 7, and the recycled oil 17 taken out from the vacuum degassing tank 7 is sprayed onto the oil sprayer 8b. The second point is that the inert gas 22 is made to leak into the vacuum degassing tank 7 through the leak valve 23.

Note that 24 in the figure indicates the flow of the leaked inert gas.

In the device for removing dissolved components in oil configured in this way,
By spraying unpurified oil from normal pressure to vacuum, deaeration occurs in a boiling state, and the deaeration rate can be dramatically increased. This principle will be explained with reference to FIG.

FIG. 4 is a diagram for explaining the material balance in the vacuum degassing tank 7. In Figure 4, as FkiL, i fjX
Taking the material balance for minutes, 1'J4=F(Zi-x
,)2(K,,a)j'V(xl-xl") ・-(5
) Furthermore, the total amount of gas that comes into contact with oil in the degassing tank 7 and the molar fraction of component i in the gas are as follows.

GTFR-ω+1F (Zlx 1 ) -----(6)
−1 Therefore, if we calculate xi* using the vapor-liquid equilibrium equation, we get xl”
=y i/to 1 =F (Zl −Xl )/(KIGTFR) --(
8). Therefore, by substituting equation (6) into equation (8), the following... (9) By making i=n simultaneous equations (9), find the concentration xi of each component being extracted. Can be done. The meanings of the new symbols used in equations (5) to (9) are as follows.

F: Supply amount (kg-mol/Hr:) GTFR: Total flow of gas ffi CICgrnol/Hr) L:
Extraction i (kg-mol/Hr) Z: Mole fraction in supplied P amount [-] Mole fraction of dissolved gas in X oil [-] ω: Leak gas flow rate CjC9-mol/Hr) Subscript i: Component Quantity index n: Number of components Here, approximately boiling phenomenon of supplied oil - gas (
It can be considered that there is no influence from the leakage gas 24+degassed gas in the filling section.

A boiling state occurs when the sum of the equilibrium gas phase partial pressures of the dissolved gas is greater than the pressure of the system, that is, when P
)>1'. At this time, supersaturation is hardly allowed, so it is thought that the boiling phenomenon progresses until the temperature changes from door to point P. Therefore, taking into consideration the effect of increasing KLa due to the boiling phenomenon (t't is the same for all components), KLa at the time of non-boiling is corrected, and the degree of saturation at which door=P is calculated from the following equation.

Ni2F', (Z i-"i)""CKL a]
ni' V(X I
Since Rf is very large, it can be seen that the degassing rate can be dramatically increased by utilizing the m-rising phenomenon.

Also, when there is equation (9), karari-kugasu (mouth 1"chi a+
)Q), it can be seen that Ni increases and tangent Xi can also be decreased.

Further, in order to fully demonstrate the effectiveness +E of the configuration as described above, a degassing test was conducted using the example shown below in which a mixed gas was dissolved in turbine oil.

Table 1 shows the test conditions, and Tables 2 and 3 show the composition in the oil take-out line from the vacuum degassing @7 to the pump 13, respectively. These test results are shown in Figure 5.
This figure shows a comparison with the case where the recycle oil 17 is merged with the unpurified oil 18 immediately before entering the vacuum deaeration tank 7 as shown in No. 6-j.

Vacuum degassing analysis 1 No: 0.098 m" 1/2 inch Raschig ring recycling oil sprayer Akanesa 2 packed bed top surface is I)l
Oc, i Vacuum degassing tank operating pressure: 1 o Hg abs〃
Operating temperature: 60℃ Oil supply 1ik: 0.0207 Cg-mol
/)IR As is clear from the test results in Tables 2 and 3, it is better to separate the circulation line for recycled oil J7 and the supply line for unpurified oil 18 as shown in Figure 3.
As shown in Figure 5, recycled 1 oil is used as unpurified oil 18.
The effect of removing dissolved components will be dramatically increased if it is merged with the feed line.

Furthermore, by comparing the test results in Tables 2 and 3, it can be seen that the larger the inert gas leakage flow rate, the greater the dissolved component removal effect.

As mentioned above, the embodiment shown in Fig. 3 shows the case where a packed bed is used inside the vacuum degassing tank, but the same result can be obtained even if a spray tower, perforated plate tower, or other gas-liquid contact system is used instead of the packed bed. You can change the effect.

As described in detail above, according to the present invention, it is possible to provide an apparatus for removing dissolved components in oil that can increase the degassing rate in the A'E degassing tank and improve the efficiency of removing dissolved components.

[Brief explanation of drawings]

Figure 1 is a schematic configuration diagram of a conventional example of a device for removing 8 components dissolved in oil, Figure 2 is a schematic diagram of a device for removing components dissolved in oil with the configuration shown in Figure 1, and Figure 4 is a diagram of a device for removing dissolved components in oil with the configuration shown in Figure 3. A schematic diagram for taking the mass balance around the vacuum degassing phase in the configuration, Figure 5 is a schematic diagram of the equipment for removing dissolved components in oil, in which unpurified oil and cycle oil are combined, Figure 6 is Figure 5 FIG. 2 is a schematic diagram for calculating the material balance of the vacuum degassing bucket in the configuration of FIG. 1...Oil to be purified, 7...Vacuum degassing phase, 8.
°°Oil sprayer, 10...Vacuum pump, 17
... Recycled oil, 18... Unpurified oil just before entering the vacuum degassing phase, 2o... Filled bed, 22... Inert gas to be leaked.

Claims (1)

[Claims] There is a vacuum deaeration tank in which oil in which gas and low boiling point components are dissolved flows in through a supply line and the dissolved components in the oil are diffused by vacuum degassing, and inert scum other than the dissolved components in the oil is removed into the vacuum deaeration tank. A means for leaking the oil in the vacuum deaeration tank and the inert gas, and a means for causing cycle oil taken out from the vacuum deaeration tank to pass through an oil circulation line provided separately from the supply line. A means of supplying directly to the upper part of the deaeration tank Φ
An equipment for removing dissolved components in oil similar to 11N and 48.