JPH0340573Y2 - - Google Patents

Description

[Detailed explanation of the invention] (a) Industrial application field This invention, for example, dehumidifies the resin pellets before placing them in a synthetic resin molding device such as an injection molding machine and molding a resin product. This invention relates to a dehumidifying dryer for resin pellets used for drying and crystallization (solid phase polymerization).

(b) Prior Art Conventionally, as a dehumidifying dryer for resin pellets as described above, there is, for example, an apparatus described in Japanese Utility Model Application Publication No. 101394/1983.

That is, a hopper is provided inside the resin pellets to dehumidify and dry the resin pellets, a circulation path is connected to this hopper, and a fan, a cooler, a dehumidifier, and a reheater are interposed in the circulation path. This device is configured to continuously dehumidify and dry the resin pellets inside.

However, because this conventional device uses circulating air, which is not fresh air, for drying and dehumidifying the pellets, ethylene glycol (HOCH ₂ CH ₂ OH) and moisture generated from the resin pellets may be present in the circulating air during long-term use. Contains impurities such as
Not only was the dehumidification and drying efficiency of the circulating air significantly reduced, but there was also the possibility that the circulation system would be clogged with the above-mentioned ethylene glycol.

In order to solve the above-mentioned drawbacks, the applicant of the present invention separated the circulating air system and the dehumidifying air system, used fresh air as the dehumidifying air, and created an air system capable of removing the hygroscopic air after passing through the hopper to the outside. A patent application was first made in 1983 for a dehumidifying dryer for resin pellets, which was equipped with a discharge pipe to significantly improve dehumidification and drying efficiency and prevent the circulating air system from being clogged with impurities such as ethylene glycol. - Filed as No. 22449.

In this prior invention, a circulation path communicating with the upper and middle portions of the hopper is connected to the hopper, an air circulation means and an air heating means are interposed in the circulation path, and dehumidified air is heated by the air heating means. A dehumidified air supply pipe is provided at the lower part of the hopper, and an air discharge pipe is installed at the upper part of the hopper to remove the moisture-absorbed air to the outside of the hopper.

However, the dehumidifying air heating means of the prior invention described above,
Since the circulating air heating means is shared and the dehumidified air supply pipe is inserted into the circulating air heating means and heated, the dehumidified air passes through the pipe vigorously and is heated to the high temperature required for dehumidifying and drying. There was a problem that it reached inside the hoppa without doing so.

(c) Purpose of the invention This invention can prevent the circulating air system from clogging with impurities such as ethylene glycol while improving dehumidifying and drying efficiency. The purpose of the present invention is to provide a dehumidifying dryer for resin pellets that can significantly improve dehumidifying and drying efficiency by supplying air.

(d) Structure of the invention This invention is a dehumidifying dryer for resin pellets, which is equipped with a hopper for dehumidifying and drying resin pellets.
A circulation path is provided outside the hopper to communicate the upper part of the hopper with a downwardly opened air outlet 4a in the middle of the hopper, thereby forming a circulating air system. An air outlet opening downward from a dehumidified air supply pipe for supplying dehumidified air is provided, and the circulation path is provided with an air circulation means and a heating means for heating the circulating air in the enlarged chamber, and an air outlet is provided in the middle of the dehumidified air supply pipe. is provided with a dehumidifying air heating means having a heat source provided in a heating cylinder with a large capacity, independent of the circulating air heating means, and an air heater provided in the upper part of the hopper that can discharge the hygroscopic air to the outside of the hopper. A discharge pipe is installed to configure a dehumidifying air system that discharges the dehumidified air supplied from the outlet of the dehumidified air supply pipe to the outside of the hopper through the inside of the hopper, and the inside of the hopper is connected to an area above the outlet of the circulating air system. This dehumidifying dryer for resin pellets is divided into a pre-drying section and a highly dry and heat-retaining section below the outlet.

(e) Effect of the invention According to this invention, the circulating air system and the dehumidifying air system are separated, fresh air is used as the dehumidifying air, and an air exhaust pipe is provided to remove the moisture-absorbed air to the outside. This has the effect of increasing drying efficiency while preventing clogging of the circulating air system with impurities attached to or emitted from the resin pellets, thereby enabling long-term continuous operation.

Moreover, the heating means for heating the dehumidified air is made independent from the heating means for the circulating air, and the dehumidified air heating means is formed by disposing a heat source in a heating cylinder whose volume is larger than that of the supply pipe in the middle of the dehumidified air supply pipe. Since we set up
The atmosphere in the high dryness and high dehumidification section at the bottom of the hopper can be significantly improved, resulting in even better dehumidification and drying effects and the effect of shortening the drying time.

In addition, since the interior of the hopper is divided into an upper pre-drying section and a lower high-dry heat retention section, the resin pellets are heated and pre-dehydrated in the upper pre-drying section.
Since the pre-dried resin pellets are subjected to dehumidification, high drying and heat retention treatment in the lower high dry heat retention section, the resin pellets can be effectively dehumidified and dried. In other words, since the water and impurities such as ethylene glycol that are dehydrated from the resin pellets are released from the air discharge pipe in advance during pre-drying of the resin pellets, the water and impurities are removed faster than when the pellets are dehumidified and dried at the same time. The amount of re-adhesion to pellets during drying can be significantly reduced, and effective dehumidification and drying can be performed.

Furthermore, since the above-mentioned two systems (circulating air system and dehumidifying air system) are used, it is possible to prevent clogging of the circulating air system while improving dehumidifying and drying efficiency with respect to unit power consumption of heat sources such as heaters. There is.

(F) Embodiment of the invention An embodiment of the invention will be described below in detail based on the drawings.

The drawing shows a dehumidifying dryer for resin pellets, and in the drawing, a hopper 1 is provided inside which dehumidifies and dries resin pellets A made of, for example, polyester. 2, an inlet (not shown) for the resin pellets A is formed at the upper end of the hopper 1, and an outlet 3 for the resin pellets A is formed at the lower end of the hopper 1.

On the outside of the above-mentioned hopper 1, there is a downward flange-shaped air outlet 4 that opens at the upper end of the hopper 1, at the radial center of the hopper 1, and at approximately the center in the vertical direction.
A circulation path 4 that communicates with a is connected for communication.

A blower 5 as an air circulation means and a heating cylinder 6 having an enlarged chamber structure as a circulating air heating means C are interposed in this circulation path 4, and a heating cylinder 6 is connected to a heater power source 7. A heater 8 is provided.

On the other hand, the flat-shaped outlet 9a of the dehumidified air supply pipe 9
is provided below the hopper-shaped air outlet 4a of the hopper 1, and on the upstream side there is an on-off valve 10 and a dehumidifier 1.
1, an air compressor 12 as a fresh air supply source is connected.

Then, the on-off valve 1 of this dehumidified air supply pipe 9
0, a dehumidified air heating means D consisting of a heater 8a connected to a heater power source 7 is arranged in a heating cylinder 6a having a larger volume than the supply pipe 9, and an air compressor 12. The dehumidifier 11 dehumidifies the fresh air pumped from the dehumidifier 11, and the dehumidified high-temperature air is slowly and sufficiently heated in the independent dehumidified air heating means D.
The structure is such that the water is supplied from the hopper 1 to the lower part of the hopper 1.

Furthermore, an air discharge pipe 13 is attached to the upper end of the hopper 1 to discharge the moisture-absorbed air to the outside of the hopper 1, and a discharge valve 14 is interposed in the air discharge pipe 13.

With this configuration, the high-temperature circulating air heated by the circulating air heating means C is directed by the blower 5 into the direction indicated by the arrow b.
Circulating air system X that circulates in the direction and dehumidifies fresh air,
Two air systems X and Y can be formed separately from the dehumidifying air system Y which discharges heated dehumidified high-temperature air in the direction of arrow a, and the air discharge pipe 13 discharges the hygroscopic air to the outside at regular intervals. The inside of the hopper 1 can be divided into a pre-drying section S1 above the middle part and a highly dry heat-retaining section S2 between the lower part of the hopper and the middle part of the hopper.

Here, since the dehumidified high-temperature air supplied in the direction of arrow a is supplied by the high-output air compressor 12, the air from the upper pre-drying section S1 does not flow into the high-drying and heat-retaining section S2; A partition means such as a flexible sheet or an opening/closing shutter may be provided at the boundary between these sections S1 and S2.

In the drawings, the circulating air heating means C and the dehumidifying air heating means D are explained in a connected state, but it is of course possible to arrange both the heating means C and D separately and independently.

The illustrated embodiment is configured as described above,
The action will be explained below.

The resin pellets A... put into the hopper 1 are
First, in the upper pre-drying section S1, the temperature is raised by high-temperature circulating air supplied from the flap-like outlet 4a in the direction of arrow b, and preliminary dehydration is performed.

By taking out the treated resin pellets A from the above-mentioned take-out port 3, the resin pellets A in the above-mentioned pre-drying section S1 naturally flow down into the lower high-dry heat-retaining section S2, and are In this step, crystallization is successively promoted while being dehumidified, highly dried, and kept warm by dehumidified high-temperature air supplied in the direction of arrow a from the trumpet-shaped outlet 9a at the tip of the dehumidified air supply pipe 9.

When the resin pellets A are dehumidified and dried, impurities such as ethylene glycol and water are generated from the pellets A. These impurities are discharged together with the air flowing inside the hopper 1 from the bottom to the top. It is periodically released from the pipe 13 to the outside of the hopper 1 and removed.

In this way, an air compressor 12 is connected to the dehumidified air supply pipe 9 which is separated from the circulation path 4 of the circulation air system X.
When fresh air is supplied from the hopper 1, this fresh air is dehumidified and heated before being supplied into the hopper 1 from the center of the lower part of the hopper 1. After dehumidifying and drying the resin pellets A, the hygroscopic air becomes the ethylene glycol The hopper 1 is periodically discharged from the air discharge pipe 13 with impurities such as
Since the impurities are removed to the outside, the amount of impurities mixed into the circulating air circulating in the direction of arrow b can be significantly reduced, and the downtime for cleaning filters and the like can be reduced.

In addition, inside the hopper 1 described above, there is an upper pre-drying section S1 and a lower high-dry heat-retaining section S.
Since the pellets can be separated into the resin pellets A and 2, the resin pellets A can be effectively dehumidified and dried.

Furthermore, the dehumidified air heating means D is separated and independent from the circulating air heating means C, and the heater 8a as a heat source is provided in the heating cylinder 6a, which has a larger volume than the dehumidified air supply pipe 9. Compared to simply passing a dehumidified air supply pipe through the circulating air heating means C, the dehumidified air is sufficiently heated and raised in temperature while temporarily staying in the heating cylinder 6a, which has a larger volume.

For this reason, the atmosphere in the highly dry heat-retaining section S2 below the hopper 1 becomes extremely hot and dry, and an excellent dehumidifying and drying effect on the resin pellets can be expected.

[Brief explanation of the drawing]

The drawing is a longitudinal sectional view showing the dehumidifying dryer for resin pellets of this invention. 1... Hopper, 4... Circulation path, 4a... Air outlet, 5... Air circulation means (blower), 6, 6a...
...Heating tube, 8, 8a... Heater, 9... Dehumidified air supply pipe, 9a... Air outlet, 13... Air discharge pipe,
A... Resin pellets, C... Circulating air heating means,
D...Dehumidifying air heating means, X...Circulating air system, Y
...Dehumidifying air system.

Claims (1)

[Claims for Utility Model Registration] A dehumidifying dryer for resin pellets, which is equipped with a hopper 1 for dehumidifying and drying resin pellets A; Air outlet 4a that opens downward
A circulating air system X is constructed by providing a circulation path 4 that communicates with The circulation path 4 is provided with an air circulation means 5 and a heating means C for heating the circulating air in the expansion chamber 6, and a volume is provided in the middle of the dehumidifying air supply pipe 9 independently of the circulating air heating means. A dehumidified air heating means D comprising a heat source 8a is disposed in a heating cylinder 6a having a large diameter, and an air discharge pipe 13 is attached to the upper part of the hopper 1 to discharge moisture-absorbed air to the outside of the hopper 1.
A dehumidifying air system Y is constituted that discharges dehumidified air supplied from the outlet 9a of the dehumidified air supply pipe 9 to the outside of the hopper 1 through the inside of the hopper 1, and the inside of the hopper 1 is discharged from the outlet 4a of the circulating air system X. A dehumidifying dryer for resin pellets, which is divided into an upper pre-drying section S1 and a highly dry heat-retaining section S2 below the air outlet 4a.