JPS6225411B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a shaft sealing method and apparatus having a simple structure and a long shaft sealing life.

In a reactor equipped with a stirrer to carry out the reaction,
It is important to properly seal the rotating shaft of the stirrer to prevent leakage of reactive fluids, such as reaction vapors, reactive gases, etc. from inside the reactor.

Conventionally, various shaft sealing devices have been used as shaft sealing methods for reactors and the like. For example, the hardware that rotates with the shaft inside the nail box and the hardware that is fixed to the ground are brought into complete contact with each other, sliding on the contact surface, and airtight.
Mechanical seals, which have a structure that maintains liquid tightness, are used in many fields due to their excellent performance.

However, this mechanical seal has a complicated structure and is difficult to operate, and the sliding parts and seals are difficult to operate.
A drawback is that reactive liquids and gases come into contact with sealing materials such as gaskets, and are susceptible to corrosion or reaction, resulting in failure.

As a result of various studies in view of this situation, the inventor of the present invention has discovered that by using a special shaft sealing method, the defects of the conventional shaft sealing device can be overcome and its essential performance can be maximized. The invention has been completed.

That is, the gist of the present invention is to provide a cooling means for causing a refrigerant to flow through the fluid side of a shaft seal that prevents leakage of a rotating shaft in a shaft sealing method that uses packing, mechanical seals, etc. to prevent fluid leakage. 3 is provided around the rotation axis and in the axial direction of the rotation axis to form gas zones 1 and 2, and among the gas zones, the temperature of gas zone 1, which is closest to the fluid side, is lower than the temperature of the other gas zone 2. The present invention also provides a shaft sealing method and apparatus, characterized in that a refrigerant is made to flow through the cooling means 3 so as to maintain the temperature at a low temperature.

Note that in this specification, the "fluid side" refers to the side where substances for stirring and mixing and reaction are present.

In the shaft sealing method according to the present invention, a shaft sealing device as shown in FIG. 1 is used. FIG. 1 is a side sectional view showing one example of the shaft sealing device of the present invention, in which 1 and 2 are gas zones, 3 is a cooling means for refrigerant circulation, 5 is a rotating shaft, and 6
is a mechanical seal V gasket, 7 is a gland suppressor, 8 is an O-ring, 9 is a mechanical seal fixed ring, 10 is a mechanical seal rotating ring, 11 is a seat seat, 12 is an inert gas injection hole, 13 and 1
3' is a refrigerant supply port and a discharge port of the cooling means 3;
15 indicates a vacuum jacket.

As shown in FIG. 1, the shaft sealing device according to the present invention has the following features:
When processing or reacting fluids, such as reactive gases, vapors of reactive substances, etc., in a reactor equipped with a stirrer,
The fluid is prevented from leaking from the shaft seal portion of the stirrer shaft for a long period of time, and moreover, stable operation can be performed.

The shaft seal device used in carrying out the present invention includes a gland packing, a Wilson seal, a mechanical seal, and other parts provided to prevent fluid leakage, and a cooling system for circulating a cooling medium to the fluid side of the shaft seal body. The means 3 is provided around the rotating shaft 5 and along the axial direction of the rotating shaft. The cooling means 3 through which the coolant flows is provided with a coolant supply port 13 and a coolant discharge port 13' in order to maintain the temperature of the gas zone 1 at a predetermined operating temperature.

In the shaft sealing device of the present invention, in addition to what is shown in FIG. 1, a cooling means 4 as shown in FIG.
A shaft sealing device provided between and around the rotating shaft can also be effectively used.

When the cooling means 4 is provided in the shaft sealing device of the present invention, it is necessary to maintain the cooling means 3 closest to the fluid side at a lower temperature than the other cooling means 4 at all times. Under these conditions, some of the condensable substances contained in the gas at the top of the tank that have an adverse effect on the shaft seal body will condense in the gas zone 1.
Return to the tank gas phase section. Gas zone 2 is gas zone 1
In order to maintain a higher temperature, the condensable substances contained in the gas that passed through gas zone 1 are reduced compared to the gas phase of the tank, and in gas zone 2,
Even though the concentrations of condensable substances in the gas at the upper end of gas zone 1 and gas zone 2 are equal, gas zone 1 is in a saturated state, so in gas zone 2,
It becomes dry, so the condensable substances no longer condense, and the negative impact on the shaft seal body is drastically reduced.

Cooling means 3 and 4 in the shaft sealing device of the present invention
is not particularly limited as long as it has a structure that can achieve the object of the present invention, but for example, a jacket chamber structure as shown in FIGS. 1 and 2, or a third
Preferable cooling means include those using cooling tube groups as shown in the figure and combinations thereof.

In addition, in the shaft sealing device of the present invention, in order to further increase the shaft sealing effect, an inert injection hole is provided between the shaft seal body and the cooling means as shown in FIGS. 1 and 2.
2, and inert gas is preferably injected once or all the time to make it even more difficult for fluid to flow into the gas zone between the cooling means and the rotating shaft.

In addition, as shown in FIGS. 1 and 2, since the cooling means 3 and 4 are normally housed inside the reactor, they are easily affected by the temperature of the reactor. It is also possible to provide a vacuum jacket chamber 15 for a heat insulating structure.

In the shaft sealing device of the present invention, gas zones 1 and 2 are formed between the cooling means 3 and the rotating shaft 5.
The size of gas zone 2 is not particularly limited as long as the object of the present invention can be achieved, but it is preferable that gas zone 2 be larger than gas zone 1, as shown in FIGS. 1 and 2.

Further, in the present invention, since it is desirable that the gas in the tank should not flow into the gas zone 2 as much as possible, it is preferable that the gap between the inner surface of the cooling means 3 provided in the gas zone 1 and the outer surface of the shaft be as narrow as possible.
In some cases, it may be preferable to install a resistor such as a labyrinth seal or a screw.

The temperature of gas zone 2 needs to be equal to or higher than the temperature of gas zone 1, but a lower temperature is preferable in view of the effect on the material of the shaft seal body, and usually a maximum of 80
The temperature is preferably 40°C or lower, more preferably 40°C or lower. The temperature difference between gas zone 2 and gas zone 1 is desirably large, and is usually 1°C or more, preferably 5°C or more, and more preferably 10°C or more. The temperature of gas zones 1 and 2 is regulated by cooling means 3 and, if provided, by cooling means 3 and 4, which are equipped with a temperature control device;
Since there are cases where the temperature automatically becomes higher than the temperature of the gas zone 1 due to the gas phase gas temperature of the normal tank, etc., the cooling means 4 does not necessarily need to be provided in such a case.

The shaft sealing device of the present invention can be effectively used by being installed in various reactors, stirring tanks, etc., and is particularly stable for a long period of time compared to conventional shaft sealing devices when used in polymerization reactors for polymerizing polymerizable substances. It has the advantage that it can be used for

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto.

Example 1 In order to test the performance of the shaft sealing method according to the present invention, a shaft sealing device having the structure shown in FIG. 1 was attached to the upper part of a reaction tank as shown in FIG. 4. The reaction tank has a capacity of 5000 and the stirrer is of an anchor type. -10 to jacket chamber 3 of the shaft seal part
-5°C refrigerant was passed through.

Under this shaft-sealing condition, 92 parts by weight of methyl methacrylate, 8 parts by weight of methyl acrylate, n
- Polymerization raw materials consisting of 0.17 parts by weight of octyl mercaptan and 0.003 parts by weight of di-t-butyl peroxide are continuously fed, and the polymerization rate is approximately 63% while stirring.
A partial polymer was produced (polymerization temperature = 172°C). Continuous operation was carried out for 350 days under these polymerization conditions, but there was no leakage of the polymerization raw material from the shaft seal, and no polymer was attached to the shaft seal.

Example 2 A shaft sealing device as shown in FIG. 2 was attached to the upper part of the reaction tank as shown in FIG. 4, and the method of Example 1 was repeated (however, the jacket chamber 3 of the shaft sealing part was
-5°C refrigerant and +7°C in jacket compartment 4.
~+35°C refrigerant). After 400 days of continuous operation, there was no leakage of polymerization raw materials from the shaft seal, and no polymer adhesion at the shaft seal.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of a shaft sealing device showing one specific example of the present invention, FIGS. 2 and 3 are side sectional views showing other examples of the shaft sealing device, and FIG. 4 is a shaft sealing device for a reaction tank. It is a side sectional view showing an example when the device is installed, 1 and 2 are gas zones, 3 and 4 are cooling means for refrigerant circulation, 5 is a rotating shaft, 6 is a mechanical seal V packing, 7 is a gland suppressor, 8 is an O-ring, 9 is a mechanical seal fixed ring, 10 is a mechanical seal rotating ring, 11 is a seat seat, 12 is an inert gas injection hole, 13, 13', 14 and 14' are refrigerant supply and discharge ports, 15 16 indicates a vacuum jacket, and 16 indicates a shaft sealing device.

Claims (1)

[Claims] 1. In a shaft sealing method that uses packing and mechanical seals to prevent fluid leakage, a cooling means 3 that allows a refrigerant to flow is placed on the fluid side of the shaft seal that prevents leakage of the rotating shaft. gas zones 1 and 2 are formed around the rotating shaft and in the axial direction of the rotating shaft, and the temperature of gas zone 1, which is closest to the fluid side of the gas zones, is maintained at a lower temperature than the temperature of other gas zones 2. A shaft sealing method characterized in that a refrigerant is made to flow through the cooling means 3. 2. The shaft sealing method according to claim 1, wherein the cooling means 3 is comprised of a jacket chamber and/or a group of cooling pipes. 3. In a shaft sealing device that uses packing and mechanical seals to prevent fluid leakage, a cooling means 3 that allows a refrigerant to flow is installed around the rotating shaft on the fluid side of the shaft seal that prevents leakage of the rotating shaft. A shaft sealing device characterized in that it is provided in the axial direction of the shaft. 4. The shaft sealing device according to claim 3, wherein the cooling means 3 comprises a jacket chamber and/or a group of cooling pipes.