JP2001105319A - Inside cleaning method for plastic manufacturing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inside cleaning method for a plastic manufacturing device, capable of safely performing a cleaning work, efficiently removing contamination, and shortening the time up to the start of operation. SOLUTION: In the cleaning method by which cleaning materials 21 are blasted to clean the inside of a plastics manufacturing device under condition where the loss tangent of the cleaning materials 21, expressed by tanδ=G"/G' is 0.01 or more when G" is the loss elastic modulus and G' is the storage elastic modulus, energy transmitted from outside is absorbed into and adhered to a contaminated member 100 by the viscosity of the cleaning materials 21, and when the contaminated member is dropped, the contamination is stripped by an amount equivalent to the energy. As a result, since the contamination is removed quickly, the cleaning time is shortened, and the time up to the start of operation is also shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for cleaning the inside of a plastic manufacturing apparatus.

[0002]

2. Description of the Related Art For example, dirt adhering to or accumulating on equipment in petroleum equipment and petrochemical factory equipment and the like differs in substance depending on the characteristics of the equipment, and the form of adhesion and accumulation differs. To clean such equipment,
2. Description of the Related Art Conventionally, there are known a method of removing dirt by hitting and peeling using a rag or a hammer, and a method of using a shot blast method. In this shot blasting method, in general, water, sand, fine iron balls, etc., which are easily available and inexpensive, are used as a cleaning material for removing dirt, and the cleaning material is removed using a pneumatic nozzle. Cleaning is performed at a high speed while spraying and colliding with dirty surfaces.

[0003]

However, in the method (1), the work is performed inside a narrow device, and the work is dangerous due to high temperature or poor scaffolding. Becomes longer. In the method of (1), when cleaning dirt on petroleum and petrochemical factory equipment, after the cleaning is completed, when starting operation of the equipment, ensure that the abrasive used for cleaning does not mix as foreign matter in the product, and In addition, careful removal and cleaning of the abrasive material is required so as not to hinder the reactivity of the raw material, and there is a problem that the time until the start of operation becomes long.

In the method (1), when the contaminant is a plastic polymer (for example, polystyrene, polyethylene, polypropylene, etc.), the polymer has a large elastic force, so that the water, sand, fine iron balls and the like are cleaned. In the wood,
Even if they are jetted and collided at high speed, most of the force is reflected in the opposite direction and escapes, so the efficiency is poor, the speed of removing dirt is very slow, the cleaning period inside the equipment is long, There is a problem that the time until the start of operation becomes long.

An object of the present invention is to provide a method for cleaning the inside of a plastic manufacturing apparatus, which can perform a safe cleaning operation, can efficiently remove dirt, and can shorten the time until the start of operation. To provide.

[0006]

According to the first aspect of the present invention, there is provided a method of cleaning the inside of a plastic manufacturing apparatus for cleaning the inside of a plastic manufacturing apparatus by spraying an abrasive for removing dirt. When the loss modulus and G ′ are the storage modulus,
The method for cleaning the inside of a plastic manufacturing apparatus, wherein a loss tangent of the abrasive material represented by tan δ = G ″ / G ′ is 0.01 or more.

In the present invention, since the value of the loss tangent of the abrasive material is larger than that of iron or the like, the energy transfer to the contaminated member and the coefficient of friction are large, the When the energy is absorbed and adhered to the dirt member due to the viscosity of the abrasive material, the dirt is stripped off by the amount of the energy when falling. As a result, dirt is quickly removed, so that the cleaning time is reduced, and the time until the start of operation is reduced. In addition, since cleaning is performed by spraying an abrasive material, safety is improved as compared with a conventional operation of hitting and peeling using a rag or a hammer.

[0008] In the present invention, the abrasive material is a material to be sprayed on a contaminated portion of a plastic manufacturing apparatus, and is not limited to a material as long as the loss tangent is 0.01 or more. Rubber, fiber,
Any member such as a composite member may be used. However, since dirt adhering to the plastic manufacturing apparatus is often a plastic polymer such as polyethylene or polypropylene, it is preferable that the abrasive material is a polymer of the same quality. For example, for the contamination of polystyrene, polystyrene is used as the abrasive, and for polyethylene, polyethylene is used as the abrasive. The shape of the abrasive material is not limited, and may be any shape such as pellets, beads, flakes and powder. In addition, in the relationship between the dirt and the cleaning material, the use of a polishing material of the same quality as the dirt portion has a large coefficient of friction. It has been demonstrated that the sanding speed is about eight times faster for sand and about 25 times faster for cut wires and iron balls.

[0009] Here, polymers such as PP are viscoelastic substances and have properties different from metals and inorganic substances. Viscoelasticity includes dynamic viscoelasticity, in which stress and strain such as stress relaxation and creep are periodically changed and changes are observed in a short time.The dynamic viscoelasticity is a real part equivalent to elasticity and equivalent to viscosity. It is observed as a complex number with an imaginary part. Then, the above real part is stored elastic modulus (dynamic elastic modulus).
G ′, and the imaginary part is a loss modulus G ″. The ratio (G ″ / G ′) between the loss elastic modulus and the storage elastic modulus is called a loss tangent (tan δ). Such a loss tangent tan δ is substantially zero for metals and the like.
As shown in the figure, a value of about 0.01 to 0.1 is maintained. That is, the energy of 1% to 10% is dissipated, in other words, the transmission of energy to the projecting object (dirty portion) is large.

[0010] The coefficient of friction of the viscoelastic substance is expressed by the following equation. μ = K × G ″ / G ′ (W / Gr ² ) ^1/3 G ″; loss modulus G ′; storage modulus W; load As can be seen by applying a predetermined numerical value to this equation,
The friction coefficient of PP is set to be larger than that of metal or the like. For example, the friction coefficient between PP and PP is twice as large as that between metal and PP.

Further, when the wear loss amount is ∝μ, it can be considered that the case of PP coincides with the fact that the polishing depth is deep.
In addition to this, if you inject a certain amount in terms of weight,
It is also conceivable that the collision frequency is overwhelmingly increased due to the low polymer density, and that the cleaning is performed efficiently.

According to a second aspect of the present invention, in the method for cleaning the inside of a plastic manufacturing apparatus according to the first aspect, the abrasive material is
It is characterized by being of the same quality as the polymer produced by the plastic production equipment.

In the present invention, since the cause of the contamination and the cleaning material are of the same quality, the coefficient of friction increases, and when sprayed, the polishing material is absorbed by the soiled portion due to the viscosity of the cleaning material. When it is attached and falls, it will remove dirt by its energy. As a result, dirt is efficiently and quickly removed, so that the cleaning time is reduced, and the time until the start of operation is reduced.

In the present invention, the same quality means that plastic pellets, plastic beads, plastic flakes, etc., of the same material as the plastic polymer causing the stain are used as an abrasive material. If the polymer produced by the apparatus is polystyrene, it means polystyrene, and if it is polyethylene, it means polyethylene.

According to a third aspect of the present invention, in the method for cleaning the inside of a plastic manufacturing apparatus according to the first or second aspect, the abrasive is one of polyethylene and polypropylene. .

In the present invention, since the abrasive material is polypropylene or the like having a low density, if a predetermined amount is sprayed in terms of weight, it is compared with other abrasive materials such as metal and sand. The collision frequency is overwhelmingly increased. Therefore, the polishing speed is increased and the cleaning time is shortened, so that the time until the start of operation is shortened.

In the present invention, the shape of the abrasive material such as polypropylene is not limited, and may be any shape such as pellets, beads, flakes and powders.

According to a fourth aspect of the present invention, in the method for cleaning the inside of a plastic manufacturing apparatus according to any one of the first to third aspects, the shape of the abrasive is at least one of pellets and beads. Is what you do.

In the present invention, since the pellets and the like are light, storage and handling are easy, and collection is also easy.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. As shown in FIG. 1, a plastic manufacturing apparatus 1 according to the present embodiment includes a PP (polypropylene)
And a polymerization reaction tank 2 for copolymerizing ethylene with ethylene. Inside the polymerization reaction tank 2, the P
A stirring blade 4 for stirring the intermediate product (powder or the like) 3 of P is provided, and a motor 6 for rotating the stirring blade 4 is provided outside. Intermediate products (powder, etc.) 3
Is stirred by the stirring blades 4 to form a PP powder 6, and the PP powder 6 and the ethylene 15 are copolymerized, and are taken out as a polymer product (powder) 7 from an extraction nozzle 8 which is a product take-out port. I have.

A gas 9 such as an unreacted gas is circulated in the polymerization reactor 2, and a filter 10 for filtering powder in the gas and a refrigerator 11 Is provided. The ethylene 15 is sent into the polymerization reaction tank 2 together with the gas cooled and liquefied by the refrigerator 11.

As shown in detail in FIG. 2, the polymerization reaction tank 2 has a withdrawal pipe 13 for taking out the PP powder 6 from the inside of the tank 2, a level meter 14 for adjusting the product level, the motor 5, the stirring blade 4, And the manhole 8 and the like.

Next, a cleaning apparatus 20 to which the method for cleaning the inside of the plastic manufacturing apparatus 1 of the present invention is applied will be described with reference to the schematic diagram of FIG. The cleaning device 20 is for injecting PP pellets 21 as an abrasive material into the contaminated portion 100 (also shown in FIGS. 6 to 8) by air pressure, a compressor 22 that takes in air and compresses the air, and stores the compressed air. Air holder 23, a pellet hopper 24 for storing the PP pellet 21, attached to the pellet hopper 24,
A rotary valve 25 for adjusting the supply amount of the PP pellet 21 therefrom, an injection nozzle 27 for injecting the PP pellet 21, provided between the injection nozzle 27 and the pellet hopper 24, and an injection of the PP pellet 21 from the nozzle 27. A shut-off valve 28 for stopping injection, and devices 23, 25,
It comprises an injection hose 26 and the like connected over 27 and the like.

The method of using the cleaning device 20 having such a configuration is as follows: the PP pellet 21 from the pellet hopper 24 is
With the rotary valve 25 released to allow injection from the injection nozzle 27, the worker A turns the injection nozzle 27 toward a predetermined dirty portion 100 in the tank 2 and operates the shut-off valve 28. The PP pellet 21 is injected.

Here, the loss tangent of the PP pellet 21 as the abrasive is represented by tan δ = G ″ / G ′, where G ″ is the loss modulus and G ′ is the storage modulus. Its value is
It is 0.01 or more. Therefore, PP pellet 21
Since the loss tangent is much larger than that of a metal, the energy transfer is large, and the friction coefficient is large. As a result, when the PP pellet 21 is injected toward the dirty portion 100, as shown in FIG.
Absorbed by the dirt member 100 due to the viscosity of the pellet 21,
When it adheres and falls, the polished portion 100A of the dirt member 100 is peeled off by the energy thereof, so that the polished depth is increased.

On the other hand, when the small steel ball 31 is used as the abrasive, the loss tangent of the metal is almost zero, so that there is almost no energy transfer. In addition, metal vs. P
P has a very low coefficient of friction. Therefore, when the steel ball 31 is injected toward the dirty portion 100, as shown in FIG. 5, the steel ball 31 is not absorbed and adhered to the dirty member 100 and is reflected in the opposite direction. Therefore, when reflected, the polished portion 100A of the dirt member 100 cannot be peeled off. In the case of the steel ball 31, since the adhesion of the polished portion 100A is only the degree of adhesion due to collision, a deep blast depth cannot be obtained.

Next, the cleaning device 20 will be described with reference to FIGS.
The procedure of the method for cleaning the inside of the polymerization reaction tank 2 by the following will be described.
When it becomes necessary to clean the inside of the polymerization reaction tank 2, first, as shown in FIG. 6, the manhole 8 of the polymerization reaction tank 2 is opened (S 1), and preparation for extracting the inside PP powder 6 is performed. .

Next, as shown in FIG. 7, a vacuum hose 35 is inserted into the tank 2 through the manhole 8, and the PP powder 6 in the tank 2 is extracted by suction from a vacuum wheel 36 (S2). When all of the PP powder 6 in the tank 2 has been extracted, the vacuum hose 35 is pulled out of the tank 2 and then
As shown in FIG. 8, air is sucked into the tank 2 from the nozzle 18 at the lower part of the tank 2 via the vacuum hose 37 to ventilate the inside of the tank 2 (S3).

After the ventilation in the tank 2 is completed, the worker A carries the hose 26 and the injection nozzle 27 into the tank 2 and, as described with reference to FIG. By injecting, as shown in FIGS.
Polishing of the dirt member 100 contaminated with the polymer is performed. When the cleaning of the inside of the tank 2 is completed, the PP pellets 21 and the dirt and the like peeled off by the PP pellets are collected by suction using, for example, a vacuum or the like. .

According to such an embodiment, the following effects can be obtained. (1) Since the PP pellet 21 having a large value of loss tangent as compared with iron or the like, and having a large energy transfer and a large friction coefficient is used as a polishing material, the PP pellet 21 is sprayed by the injection nozzle 27. When sprayed, the PP pellet 21 is absorbed and adhered to the dirt member 100 due to its viscosity.
A is stripped off. As a result, dirt is quickly removed, so that the cleaning time is reduced, and the time until the start of operation is reduced. (2) Since the cleaning is performed by injecting the PP pellets 21 with the injection nozzle 27, the safety is improved as compared with the conventional dirt removal operation by hitting or peeling using a rag or a hammer.

(3) In the polymerization reactor 2, a product is produced by copolymerizing the intermediate product 3 of PP and ethylene 15, whereas the abrasive is PP pellet 21,
The cause of the contamination and the abrasive material are of the same quality, and the coefficient of friction increases. Also, the energy transfer is large and therefore
When injected, the PP pellets 21 adhere to the dirt member 100 due to viscosity, and when dropped, strip off dirt by the amount of energy. As a result, dirt is quickly removed, so that the cleaning time is reduced, and the time until the start of operation is reduced.

(4) In the polymerization reaction tank 2, a product is produced by copolymerizing the intermediate product 3 of PP and ethylene 15, whereas the abrasive material is the PP pellet 21.
The cause of the contamination and the abrasive material are of the same quality. Therefore, there is no danger that impurities will be mixed into the product unless it is completely recovered as in the case where the cause of the contamination and the abrasive material are foreign materials such as sand.

(5) PP pellets 21 as abrasive material
Since the density is low, if a constant amount is injected in terms of weight, the collision frequency is overwhelmingly higher than other abrasives such as sand and steel balls. Therefore, the cleaning speed is increased, the efficiency is improved, the cleaning time is shortened, and the time until the start of operation is shortened.

(6) PP pellets 21 are used as a polishing material. Since the PP pellets 21 have viscosity and can be adhered to a polymer for cleaning, for example,
Unlike the removal of dirt by the conventional shot blasting method using sand, cut wire, etc., no dust is generated, so there is no danger of dust explosion and work is easy.

(7) PP pellets 21 as abrasive material
Is easy to store and handle because of its small density and lightness, and can be easily and reliably collected by vacuum suction or the like. Further, since the collected material is the same material, it can be reused.

It should be noted that the present invention is not limited to the above-described embodiment, but may be modified as follows as long as the object of the present invention can be achieved. For example, in the above-described embodiment, the PP powder 6 is accommodated in the polymerization reaction tank 2, and the polishing of the polymerization reaction tank 2 is performed by spraying the PP pellet 21, Not limited to this. When polyethylene is contained in the polymerization reaction tank 2, polyethylene is used as an abrasive, or when polystyrene is contained in the polymerization reaction tank 2, polystyrene is used as an abrasive. May be.

[0037]

[Embodiment] A fixed amount of abrasive material is injected by weight conversion.
The situation was confirmed by cleaning the inside of the polymerization reaction tank. (1) Material used: PP pellets (2) Projection time: 90 seconds (3) Weight: 5 kg (4) Radiation air pressure: 7 kg / cm ²

[Comparative Example] [Comparative Example 1] The situation was confirmed under the same conditions as in the example by using sand as a polishing material and making the projection time longer than in the example (141 seconds).

[Comparative Example 2] A cut wire was used as an abrasive, and the projection time was slightly shorter than that of the example (80 seconds). The situation was confirmed under the same conditions as in the example.

[Comparative Example 3] An iron ball was used as a polishing material, and the projection time was set to be substantially the same as that of the embodiment.
Seconds), the situation was confirmed under the same conditions as in the example.

[Comparative Example 4] Bone was used as an abrasive material, and the projection time was set to be much longer than that of the example (16).
(0 second), the situation was confirmed under the same conditions as in the example.

Table 1 shows the results of comparison of the projection time and the blast depth of such an embodiment with Comparative Examples 1 to 4.

[0043]

[Table 1]

As can be seen from Table 1, as the abrasive material, the PP pellets of the examples showed much more efficient results than other members.

[0045]

As described above, according to the method for cleaning the inside of the plastic manufacturing apparatus of the present invention, the value of the loss tangent of the abrasive material is larger than that of iron or the like, and the energy transfer to the contaminated member can be improved. , Because the coefficient of friction is large, the energy of the blasted abrasive is absorbed and adhered to the dirt member due to the viscosity of the blasted material, and then the dirt is stripped off by the amount of the energy when falling. . As a result, dirt is quickly removed, so that the cleaning time is reduced, and the time until the start of operation is reduced.

Further, since the cleaning is performed by spraying the abrasive material, the safety is improved as compared with the conventional work by hitting and peeling using a rag or a hammer.

[Brief description of the drawings]

FIG. 1 is an overall schematic diagram showing a plastic manufacturing apparatus according to one embodiment of the present invention.

FIG. 2 is an overall vertical sectional view showing a polymerization reaction tank of the embodiment.

FIG. 3 is an overall schematic diagram showing a cleaning device for a polymerization reaction tank of the embodiment.

FIG. 4 is a schematic view showing movement of an abrasive used in the cleaning device of the embodiment.

FIG. 5 is a schematic diagram showing the movement of an iron ball when the abrasive is an iron ball.

FIG. 6 is a view showing a procedure of a cleaning method of the embodiment.

FIG. 7 is a view showing a procedure of a cleaning method of the embodiment.

FIG. 8 is a view showing a procedure of a cleaning method of the embodiment.

FIG. 9 is a view showing dynamic viscoelasticity of the polypropylene of the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Plastic manufacturing apparatus 2 Polymerization reaction tank 20 Cleaning apparatus for polymerization reaction tank 21 PP pellet as abrasive material 27 Injection nozzle 31 Steel ball as abrasive material 100 Dirty member

Claims (4)

[Claims] 1. A method for cleaning the inside of a plastic manufacturing apparatus, wherein a polishing material for removing dirt is injected to clean the inside of the plastic manufacturing apparatus, wherein G ″ is a loss modulus and G ′ is a storage modulus. When tan
The loss tangent of the abrasive material represented by δ = G ″ / G ′ is
A method for cleaning the inside of a plastic manufacturing apparatus, which is 0.01 or more. 2. The method according to claim 1, wherein the blasting material is of the same quality as the polymer produced by the plastic manufacturing apparatus. . 3. The method for cleaning the inside of a plastic manufacturing apparatus according to claim 1, wherein the blasting material is any one of polyethylene and polypropylene. . 4. The method for cleaning the inside of a plastic manufacturing apparatus according to claim 1, wherein the shape of the abrasive is at least one of pellets and beads. How to clean inside.