JPH0761684B2 - Method and apparatus for supplying cold air for film forming in blown film production - Google Patents

Description

TECHNICAL FIELD The present invention relates to the supply of cold air for film formation in the production of inflation films such as polyethylene films and polypropylene films using an extruder.

(Prior Art) Conventionally, in the production of blown film, as a positive means for increasing the film forming speed and improving the mechanical strength and optical properties of the film,
When a film is extruded from a die of an extruder and expanded into a thin film, the periphery of the film is cooled by an air flow blown from an air cooling ring.

The most general method of film cooling means at the time of film formation is to use the air around the place where the extruder 1 is installed as it is as shown in FIG. That is, the blower 2 is installed near the extruder 1, the ambient air is sucked from the blower 2, and the air 6 is blown out at high speed from the wind direction ring 4 provided on the outside of the film extrusion die 3.
The surface of the film 5 was cooled during film formation.

Therefore, it is essential to control the cooling at the time of film formation to improve the quality and increase the film production rate by the means of this type of prior art because of the influence of the fluctuation of the temperature of the ambient air used for cooling. It was impossible.

For this reason, various ideas have been made regarding the mechanism of the wind direction ring 4, but basically it is difficult to control the state of film cooling by using an air source that is subject to disturbance of the surrounding environment, and further increase in the blower capacity and the wind direction ring. The mechanism has become complicated.

Furthermore, in recent years, film forming conditions using thermoplastic resins with extremely low melt tension require more precise film forming conditions than before, and contrary to this, so-called high value-added high quality that is required to increase productivity Demand for films is increasing, and means for using the cooled and cooled air 6A using the compression refrigerator 7 as shown in FIG. 9 as the state control of the film 5 at the time of film formation capable of coping with this demand. Was proposed.

In the means using the compression type refrigerator 7, the air 6A for cooling the film, which is blown out from the wind direction ring 4 to the surface of the film 5, does not undergo the fluctuation of the environmental temperature around the extruder 1 and forms the film. Since it is possible to set the air flow temperature, the wind speed, and the air volume for controlling the state, it is possible to homogenize the physical properties of the film 5 to be produced and to make the production speed constant throughout the year. However, the method and apparatus for supplying the cold air for cooling the film by using the compression refrigerator 7 has various problems and drawbacks as described below. That is, firstly, it is necessary to consume electric power as an energy source for driving the compression refrigerator 7.

This was due to the fact that the film manufacturing industry is an electric power consumption industry and the ratio of electric power cost to the cost cost is high.

Even when the compression refrigerator 7 is used, the air itself that is sucked and cooled by the air cooler 8 must be sucked from around the extruder 1, and this sucked air is discharged from the heater 9 portion of the extruder 1. Since the temperature of the air is increased by receiving heat, the load of the compression refrigerator 7 is not merely on the cold air for cooling the film, but rather on the proportion of the heat exhausted from the heater 9 of the extruder 7 that is processed. Exists.

This is especially noticeable when the refrigerator efficiency decreases in summer and the factory temperature rises.

Therefore, the capacity of the compression refrigerator 7 must be selected with the maximum value that allows for the exhaust heat of the heater 9 of the extruder 1 as well, which increases the initial cost, the running cost and the film. It was a factor that pushed up the production cost.

In existing film manufacturing factories, it is extremely difficult to change or expand power receiving equipment both financially and physically (rewiring work, etc.). It is becoming difficult to compete with low-priced general-purpose films year by year.

The second problem existing in the cooling means and method using the conventional compression refrigerator 7 is the following point.

That is, at present, it is unavoidable to use CFCs as a refrigerant for the compression refrigerator 7, and if the refrigerant leaks due to a failure or accident of the refrigeration system, the extruder 1 is used. There is a very high possibility that the CFC refrigerant will be mixed into the raw material supply port 10.

This CFC-based refrigerant is generally stable, but when the temperature is extremely high as in the melting part of the extruder 1 and the temperature is high, the refrigerant turns into phosgene gas and exhibits extremely strong toxicity.
For this reason, the phosgene-ized CFC-based refrigerant partially destroys the cross-linked structure when a polymerization reaction of polyethylene film, polypropylene film, etc. occurs and a cross-linked structure is created.
It will be a factor of quality deterioration in the future.

The possibility that the CFC-based refrigerant may be mixed in before the leakage accident of the CFC-based refrigerant becomes a phenomenon is sufficiently conceivable in the conventional compression refrigerator 7 facility, and after the fact that the product has been shipped Processing is almost impossible.

For this reason, when the conventional compression refrigerator 7 is installed in the film manufacturing factory, it is necessary to install a machine room outside the factory, which increases the initial cost, and the cooling air supply device is widely used in the film manufacturing industry. It was also one of the difficult causes.

The third problem is exhaust heat pollution and noise pollution when a cold air supply device using the compression refrigerator 7 is introduced.
That is, as pointed out in the first problem, when the cold air required for controlling the film state during film forming is produced, the exhaust heat from the heater 9 parts of the extruder 1 is also included as a load. , The calculation load is increased accordingly.

Generally, when the compression refrigerator 7 is operated in a temperature zone of about cooling, it is necessary to finally release the heat of condensation of about 1.25 to 1.3 times the load required for cooling to the atmosphere. There is a cooling tower or an air-cooled fin coil type condenser (air-cooled condenser) as a concrete means for this. However, depending on the location conditions of the film manufacturing factory, there is a possibility of being subject to pollution control. The working environment of the people engaged in the manufacturing work could not be improved as expected (as a result of considering the increase of exhaust heat quantity and running cost due to the introduction of the air conditioner etc.), the number of people who wanted to work in the film manufacturing factory decreased. It was also the cause of the loss. that's all,
As described in detail, in the extension of the conventional technology, various problems have not yet been solved, and the conventional cooling mechanism at the time of film formation is sufficient to satisfy the demands of the industry when viewed comprehensively. It wasn't a means.

(Technical Problem) Therefore, the present invention has been made in view of the drawbacks of the prior art, and various problems are involved in the environmental preparation and control of the film surface state required at the time of film production and molding in the conventional extruder. As a specific means for solving them, the exhaust heat from the heater of the raw material melting part which constitutes the extruder is reused as the driving energy source of the adsorption refrigerator and the cold air (+ 7 ° c ~ By obtaining the high-quality and high-value film products required by the film manufacturing industry at a low cost by controlling the condition during film forming by obtaining the temperature range up to + 25 ° C) The purpose of the present invention is to propose a pollution-free cold air supply device that does not use CFC refrigerants.

(Technical Means) In order to solve the above technical problem, the present invention uses not the electric power but the exhaust heat from the heater portion of the extruder as the energy source of the refrigerator that causes heat transfer.

Further, as the refrigerator itself, a static adsorption type refrigerator having no mechanical moving parts is used, and the surface of the film is cooled by the cold air supplied by the refrigerator at the time of forming the film from the extruder.

In particular, as a means for effectively and efficiently exhausting heat from the heater part of the extruder (meaning reducing temperature drop loss and increasing heat flux absorption), a heat exchanger for exhaust heat absorption of a heater composed of a heat pipe Is to have. That is,
When the means according to the present invention is used in a general film extruder, a heat pipe type heat exchanger group surrounding a heater portion for heating provided outside the melting cylinder of the extruder is arranged, and convective heat transfer and radiant heat of air are arranged. About 95% of heat due to transfer
Adopt a structure that efficiently absorbs to a certain degree.

Most of the exhaust heat can be absorbed by adopting this heat pipe type heat exchanger, so unlike the conventional method, heat diffusion to the surroundings of the extruder does not occur and only the film cooling load needs to be processed, and a mechanical cooling device is required. The air volume is reduced, the cooling air velocity is also reduced, and as a result, the capacity of the blower is reduced and the working environment of the manufacturing worker is improved. The energy of the exhaust heat absorbed by this heat pipe heat exchanger (energy to ambient temperature determined by temperature and heat flux density) is transferred to hot water, and this hot water is transferred to silica gel (porous adsorption) inside the adsorption refrigerator. The temperature of the silica gel will be raised in a hot water heat exchanger located in the material (having the surface).

Silica gel adsorbing water vapor and being in a saturated state cannot withstand the increase in the molecular motion of water vapor activated by the temperature rise, and releases water vapor. (Silica gel has a correlation that exists between the amount of water vapor adsorption and the surface temperature of silica gel with ambient pressure as a parameter.) Thus, using an adsorption refrigerator that uses water as a refrigerant as a technical means, As a result, the air cooled and cooled is obtained, and thereby the original purpose of forming the film extruded from the film extruder is controlled.

Since the present invention constitutes the cold air generating mechanism by utilizing the exhaust heat from the heater part of the film extruder as described above, the power consumption required in comparison with the conventional cold air generating device by the compression type refrigerator using electric input Is extremely small and the total amount of heat released to the outside from the entire apparatus is about 50% or less than that using a compression refrigerator.

Specifically, it has the following configuration as shown in the drawing.

An extruder 20 has a mixing / conveying screw 22 rotatably provided in its cylinder 21.

Reference numeral 23 is a screw drive motor for rotating the mixing / conveying screw 22 in a predetermined direction at a predetermined speed.
24 is a hopper, and the solid material 26 of the film is a cylinder
It is to be put into 21. Reference numeral 25 is a heater ring wound around the outside of the cylinder 21 as a raw material melting heater to melt the raw material 26 of the film to make it into a fluid state. The melted and fluidized raw material 26A is transferred to the die (extruded annular ring) 27 by the mixing / conveying screw 22.
Is pushed into.

28 is a heat pipe type heat exchanger and is provided at an appropriate position of the cylinder 21 in which the heater ring 25 is arranged, as shown in FIGS. 2 and 4.

Reference numeral 29 denotes a metal heat-absorbing fin that constitutes a part of the heat pipe type heat exchanger 28, which absorbs heat radiated from the heater ring 25 and transmits it to a hot water heating pipe portion 30 which forms a heat radiating portion, and the closed circulating hot water is supplied. Heat is applied to the hot water 32 forming the circuit 31.

The hot water 32 is about 70 ° to 90 ° C.

Reference numeral 33 denotes a heat insulating cover lined inside the casing cover 34.

A hot water tank 35 constitutes a part of the closed circulating hot water circuit 31, and the hot water 32 is constantly circulated by a pump 36.

Reference numeral 37 is an adsorption refrigerator constituting a closed housing (37A), which mainly condenses steam with a first chamber 38 and a second chamber 39 in which silica gel Si is hermetically filled and a cold water chamber 41 having cold water 40 as a water refrigerant. And a return pipe 43 for returning condensed water to the cold water chamber 41. The pressure inside the closed housing 37A is maintained at 0.02 kg / cm ² at room temperature. As shown in FIG. 5, the arrangement of the chambers (38, 39, 41, 42) is such that the lower left and right chambers are the first and the second chambers (38, 39). Condensing chambers 42 are arranged above the respective 41.

Reference numeral 44 denotes a first steam chamber which is occupying a space above the first chamber 38, and 45 is a second steam chamber which is occupying a space above the second chamber 39.

Thus, the first steam chamber 44 and the condensation chamber 42
Are communicated with each other via a check valve 46 that operates at a slight differential pressure, and the second steam chamber 45 and the condensation chamber 42 are also communicated with each other via a check valve 47. Further, the first steam chamber 44 and the cold water chamber 41 have a check valve 48 that operates at a slight differential pressure.
The second steam chamber 45 and the cooling chamber 41 communicate with each other via a check valve 49. Therefore,
First steam chamber 44 and second steam chamber 45
And is switched by the timing operation of these check valves (46, 47, 48, 49). 50 is the first chamber
38 is connected to the first heating side solenoid valve 51 of the closed circulating hot water circuit 31 by the first coiled heating tube inserted and arranged in the silica gel Si, and the first heating side solenoid valve 51 is "Open"
At this time, the hot water 32 in the hot water heating pipe portion 30 is made to flow into the hot water tank 35 through the pipe line 31A, the first heating side solenoid valve 51, the coiled heating pipe 50, and the pipe line 31B. is there.

Reference numeral 52 is a second coil-shaped heating tube inserted and arranged in the silica gel Si of the second chamber 39, which is the closed circulating hot water circuit.
31 is connected to the second heating side solenoid valve 53, and when the first heating side solenoid valve 51 is “closed” and the second heating side solenoid valve 53 is “open”, the hot water heating pipe section The hot water 32 in 30 is designed to flow into the hot water tank 35 through the pipe 31A, the second heating side solenoid valve 53, the coil-shaped heating pipe 52, and the pipe 31C. Reference numeral 54 denotes a first coil-shaped heat absorption tube inserted and arranged in the silica gel Si of the first chamber 38, a cooling water circuit 57 having a pump 58 and a cooling tower 56 via a first cooling side electromagnetic valve 55.
Are connected in parallel. Reference numeral 59 denotes a second coil-shaped heat absorption tube inserted and arranged in the silica gel Si of the second chamber 39, which is connected in series to the cooling water circuit 57 via a second cooling side electromagnetic valve 60.

The operation of the heating pipes (50, 52) and the endothermic pipes (54, 59) is designed to be controlled in timing as follows.

That is, when the hot water 32 is being sent through the first heating-side solenoid valve 51 to the first coil-shaped heating pipe 50 in the closed housing 37A in the adsorption refrigerator 37, the second coil-shaped The second coiled heating side solenoid valve 53 connected to the heating pipe 52 is "closed", and the first cooling side solenoid valve 55 connected to the first coiled heat absorption pipe 54 is "closed". The second cooling-side solenoid valve 60 connected to the second coil-shaped heat absorption tube 59 is configured to be “open”.

In other words, the corresponding operation of each of these solenoid valves (51, 53, 55, 60) is the first heating-side solenoid valve 51 and the second cooling-side solenoid valve 60.
The control circuit 61 always switches between the above-mentioned group and the second heating-side electromagnetic valve 53 and the first cooling-side electromagnetic valve 55 to the opposite operation at a certain fixed time interval.

Reference numeral 62 denotes a coil-shaped condensing pipe arranged in the condensing chamber 42, which is connected in parallel to the cooling water circuit 57 and constantly circulates the cooling water.

Reference numeral 63 denotes a coil-shaped cold water main pipe arranged at the bottom of the cold water chamber 41, which is connected in series to a cold water circuit 67 having a cold water tank 64, a pump 65, and a fin coil type heat exchanger 66 so that cold water always circulates. It's done. Reference numeral 68 denotes a blower chamber having the fin coil type heat exchanger 66 described above, which sucks ambient air by a blower fan 69 and cools it. Next, the operation of the heat adsorption type refrigerator 37 described above will be described.

The above-described timing switching of the various solenoid valves (51, 60) (53, 55) is performed at intervals of about 5 minutes by the control circuit 61 that performs sequence control.

The operation in this one cycle is as follows.

Now, the first heating-side solenoid valve 51 and the second cooling-side solenoid valve 60 are “open”, the second heating-side solenoid valve 53, and the first cooling-side solenoid valve 55.
Is “closed”, the exhaust heat of the heater ring 25 portion of the extruder 20 is given to the hot water 32 through the heat absorbing fins 29 of the heat pipe heat exchanger 28 and the hot water pipe portion 30, and the first coil The silica gel Si containing water vapor, which is filled in the first chamber 38, is heated by the heating tube 50 in the shape of a circle.

The heated silica gel Si releases the retained water vapor, raises the pressure in the first water vapor chamber 44, pushes the check valve 46 open, and flows into the condensation chamber 42 where it is heated by the coiled vapor condensation tube 62. It is deprived of water and condensed to become water, which descends in the return pipe 43 and collects in the cold water chamber 41.

On the other hand, the silica gel Si in the second chamber 39 radiates heat to the cooling water in the cooling water circuit 57 passing through the second coil-shaped endothermic tube 59, and the temperature of the silica gel Si is kept close to the cooling water temperature. descend.

Therefore, the porous surface of the silica gel Si is in a state where it is extremely easy to adsorb water vapor, and the water vapor pressure in the second water vapor chamber 45 is adsorbed by the silica gel Si, resulting in a large decrease in water vapor pressure.

Then, in the cold water chamber 41 and the second steam chamber
A pressure difference of steam is generated between the inside of 45 and the check valve 49 is pushed open, and the steam inside the cold water chamber 41 is the second steam chamber.
It moves into 45 and is adsorbed on silica gel Si.

As a result, the pressure in the cold water chamber 41 is prevented from dropping, the water 40 accumulated in the cold water chamber 41 is vigorously vaporized and turned into steam, and the heat of vaporization lowers the water temperature in the cold water chamber 41.

Therefore, a coiled cold water main pipe passing through the cold water chamber 41
The cooling water for air cooling, which is closed and circulated in the cooling water circuit 67 where it flows in 63, is cooled.

This cold water cools the air in the fin-coil heat exchanger 66 and repeats the cycle to generate cold air, which is used for controlling the state of the film surface.

Now, before the silica gel Si adsorption phenomenon of the second water vapor chamber 45 reaches saturation, the first water vapor chamber
The first heating-side solenoid valve 51 communicating with the first coil-shaped heating pipe 52 on the 44 side is “closed”, and the first cooling-side solenoid valve 55 is “open”, so that the first steam chamber 44 The cooling of the silica gel Si that has released the water vapor is started, and the silica gel Si in the first water vapor chamber 44 is also gradually cooled in the cold water chamber 41.
It absorbs more water vapor (at this time, the check valve 48 is “open”) and contributes to the production of cold water.

Here, if the switching time comes, the second heating side solenoid valve
When 53 is “open” and the second cooling-side solenoid valve 60 is “closed”, the heating of the silica gel Si that has absorbed and saturated the water vapor in the second water vapor chamber 44 begins, and when the water vapor begins to be released, the second The pressure inside the water vapor chamber 45 increases and the check valve
47 is pushed open, and the heated steam flows into the condensation chamber 42 and is condensed and liquefied.

At this time, the silica gel in the first steam chamber 44 has already been
Since Si adsorbs water vapor in the cold water chamber 41 and lowers the water temperature in the cold water chamber 41, the cold water for cooling the air in the cold water circuit 67 continues to be cooled. As described above, in the adsorption refrigerator 37, cold water is constantly produced by the difference between the exhaust heat of the heater ring 25 in the extruder 20 and the ambient temperature (atmospheric temperature). This cold water circulates in the fin-coil heat exchanger 66 in the blower chamber 68 to cool the ambient air 70 sucked from the blower fan 69, while heating the cold water circuit.
The cold water in 67 is cooled again in the cold water chamber 41.

On the other hand, the cooled ambient air 70 is cooled by the flexible duct tube 71 as cold air from the wind direction ring 72 to the film F.
Sprayed onto the surface of.

As shown in FIG. 7, the die 27 has a guide column 74 having a coil-shaped guide groove 73 inside, and the fluid film raw material 26A extruded from the extruder 20 is the coil-shaped guide groove. It passes through the inside of 73 and is released from the annular slit 75 as a film F in a cylindrical inflation state.

The wind direction ring 72 is arranged above the die 27 and blows cold air from the flexible duct tube 71 onto the surface of the film F.

The cold air introduced into the wind direction ring 72 is divided into the first blowing passage 76 and the second blowing passage 77 having the baffle plate 75 and blown toward the film F, respectively. In this way, the film F is cooled.

(Operation) The raw material 26 charged from the hopper 24 of the extruder 20 is melted by the heater ring 25 in the cylinder 21 to be in a fluid state, and sent to the die 27 by the mixing / conveying screw 22.

The heat radiated from the heater ring 25 is transferred to the hot water heating pipe section 30 by the heat pipe type heat exchanger 28 and gives heat to the hot water 32 of the closed circulating hot water circuit 31. Now the first heating solenoid valve
When 51 and the second heating side solenoid valve 60 are opened, the hot water 32 of the closed circulating hot water circuit 31 flows in the first coiled heating pipe 50 and forms a part of the adsorption refrigerator 37. One chamber 38
The silica gel Si containing water vapor filled therein is heated. At that time, the heated silica gel Si releases the retained water vapor, raises the pressure in the first water vapor chamber 44, pushes the check valve 46 open, and flows into the condensing chamber 42. The heat is deprived of the heat and condensed to form water droplets, which descend in the return pipe 43 and fall in the cold water chamber 41. On the other hand, the silica gel Si in the second chamber 39 radiates heat to the cooling water in the endothermic tube 59 to lower the temperature.

Therefore, the water vapor pressure in the cold water chamber 41 pushes open the check valve 49, the water vapor moves into the second water vapor chamber 45, and is adsorbed on the silica gel Si.

As a result, the water temperature in the cold water chamber 41 falls according to the above-mentioned principle, the cold water for cooling the air circulating in the cold water circuit 67 is cooled, and sucked from the blower fan 69 via the fin coil heat exchanger 66. The ambient air 70 is cooled to generate cold air for film formation, and the film F is passed through the wind direction ring 72.
Let it radiate on the surface of.

Since the operation of the present invention is continuously performed, it is suitable for forming the film F without causing the stepwise change of the cold air temperature. Then, since all the exhaust heat is released to the atmosphere without being diffused around the extruder 20, the working environment is remarkably improved as compared with the conventional method using the compression refrigerator.

Further, the cold air generator using the exhaust heat according to the present invention has less moving parts, lower failure rate, less noise, and can be installed near the extruder 20 than that using a conventional compression refrigerator. is there. Still, the price is lower than that of the conventional technology, so the industrial utility value is high.

The present invention has been described above. However, the present invention is not limited to the illustrated one, and for example, the absorption of the heater exhaust heat can be replaced with a conventional water cooling jacket type heat exchanger (not shown). In this case, the utilization efficiency of exhaust heat is inferior to that of the heat pipe type, but the essential configuration for the function of the entire device is the same.

As described above, various modifications are possible within the scope of the gist of the present invention, and these do not depart from the scope of the present invention.

(Effect) (a) The cold air supply device using the exhaust heat of the extruder according to the present invention stabilizes and strengthens the physical properties such as mechanical strength and optical properties of the blown film and stabilizes the production amount throughout the year. it can.

(B) Since the cold air supply device according to the present invention uses the physicochemical refrigerator, the power consumption of the refrigerator is extremely small as compared with the conventional compression refrigerator.

(C) Since the cold air supply device according to the present invention uses the water refrigerant instead of the CFC refrigerant, even if a refrigerant leakage accident should occur, products such as films will not be deteriorated. Moreover, it is not necessary to provide a special machine room.

(D) Since the cold air supply device according to the present invention has low exhaust heat, low noise, and low price, it can be introduced more easily than the conventional compression refrigerator technology and can contribute to the industry.

In addition, the work environment around the extruder is improved, which greatly contributes to the safety and health of workers.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view showing a connecting relationship between an extruder, a die and a wind direction ring according to the present invention, and FIG. 2 is an enlarged vertical side view showing a relationship between a cylinder around which a heater ring is wound and a heat pipe type heat exchanger. Fig. 3 is an exploded perspective view of the main part of Fig. 2,
FIG. 4 is an overall piping diagram of the present invention, and FIG. 5 is an enlarged vertical sectional front view of the adsorption refrigerator of the present invention. FIG. 6 is an enlarged vertical sectional front view of the wind direction ring, showing the left half. FIG. 7 is an enlarged vertical sectional front view of the die. FIG. 8 shows a first example of the prior art, and FIG. 9 shows a second example of the prior art. 20 …… Extruder, 21 …… Cylinder, 25 …… Heater ring, 28 …… Heat pipe heat exchanger, 31 …… Heat circulation hot water circuit, 37 …… Adsorption refrigerator, 57 …… Cooling water circuit, 67 ...
... Cold water circuit

Claims (3)

[Claims] 1. Cold water in a cold water circuit 67 via an adsorption refrigerator 37 that uses the difference between the exhaust heat temperature of a raw material melting heater of the extruder 20 and the temperature of the ambient air of the extruder 20 as a drive energy source. A method for supplying cold air for film formation in the production of an inflation film, which is configured to cool the film F at the time of film formation using the cold air obtained from 2. Exhaust heat of a raw material melting heater of an extruder 20 is absorbed by a heat pipe type heat exchanger 28 and converted into drive energy of an adsorption type refrigerator 37 to supply cold air for film cooling. Cold air supply device for manufacturing blown film 3. A heat pipe type heat exchanger 28 absorbs waste heat from a raw material melting heater of an extruder 20 and supplies the absorbed heat to hot water 32 in a closed circulation circuit 31 to activate an adsorption type refrigerator 37. The cold water 40 of the adsorption refrigerator 37 cools the cold water in the cold water circuit 67 having the fin coil heat exchanger 66, and the ambient air 70 passing through the fin coil heat exchanger 66 is cooled by the cold water in the cold water circuit 67. A cooling air supply device in the production of blown film for cooling and supplying cold air for film cooling.