Drying and gas or vapor contact with solids – Apparatus – Gravity flow type
Reexamination Certificate
2000-04-07
2001-11-27
Lu, Jiping (Department: 3749)
Drying and gas or vapor contact with solids
Apparatus
Gravity flow type
C034S168000, C034S084000, C034S585000
Reexamination Certificate
active
06321461
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a drying apparatus (equipment) for drying a powder particle such as plastic pellet, using high pressure gas, in particular, high pressure gas having a low humidity (low dew point).
Conventionally, a hopper dryer type drying apparatus has been widely known as a drying apparatus for drying a powder particle such as a plastic pellet. The drying equipment is arranged on an upper portion of an injection machine or extruder, and has a hopper receiving a plastic pellet, and a control unit which is arranged side the injection machine or extruder, and is connected with the hopper by an air supply passage and a return passage. The control unit includes a dehumidifier, a heater, a compressor, a circulating fan and the like, in its interior. Further, the control unit supplies a high pressure dry air to the hopper via the air supply passage while recovering exhaust gas after dry treatment from the hopper via the return passage, and then, dehumidifies and heats the recovered exhaust gas after dry treatment, and thereafter, again supplies the exhaust gas to the hopper via the air supply passage. In the aforesaid manner, in the drying apparatus, the exhaust gas after dry treatment is circulated, and then, is recycled, and thus, a pellet is dried. This type of control unit has been disclosed in Japanese Laid-Open Patent Publication No. Hei8-207044, for example.
By the way, a drying speed of the plastic pellet received in the hopper increases in proportion to an amount of drying air passing through the hopper. Therefore, in order to increase the drying speed of pellet, there is the need of supplying a large amount of drying air to the hopper. In order to achieve this, large-size and high performance compressor and circulating fan are required. In addition, this kind of conventional drying apparatus is constructed in the following manner; more specifically, the entire amount of exhaust gas after dry treatment from the hopper is returned back to the control unit, and then, is dehumidified in the control unit, and thereafter, is again circulated. For this reason, inevitably, the control unit must be made into a large size.
As a result, the drying apparatus is made into a large size as a whole; for this reason, there is a problem that an introduction (manufacture) cost and a running cost become high. Moreover, an installation space for the control unit must be secured; for this reason, a large-diameter air pipe (duct) is indispensable. As a result, there is a problem that a wide space is required around the injection machine or extruder, and also, a construction cost for installing the drying apparatus increases.
SUMMARY OF THE INVENTION
The present invention has been made taking the aforesaid problem in the prior art into consideration. It is, therefore, an object of the present invention to provide a drying apparatus using high pressure gas, which can perform the same dry treatment capacity as the case of using a large-size compressor with the use of a small-size compressor as compared with a conventional drying apparatus, and can economize a manufacture cost and a running cost spent for dry.
Further, another object of the present invention is to provide a drying apparatus which is constructed into a compact size as the entire apparatus, and can reduce a space spent for installation, and further, can achieve a reduction of cost spent for installation.
In order to achieve the above objects, the present invention provides a drying apparatus using high pressure gas, comprising: a drying apparatus main body including a supply port and an exhaust port, and receiving an object to be dried; and a gas supply unit for supplying high pressure dry gas to the drying apparatus main body, the gas supply unit including: a high pressure gas generating means for supplying pressurized gas; a dehumidifier for removing water content of gas; a heater for heating gas; a gas supply passage connecting the high pressure gas generating means, the dehumidifier and the heater while being connected to the supply port of the drying apparatus main body, and supplying controlled high pressure dry gas to the drying apparatus main body; and an ejector arranged on the way of the gas supply passage; an injection port of the ejector being connected with an upstream side of the gas supply passage, a discharge port of the ejector being connected with a downstream side of the gas supply passage, an intake port of the ejector being connected to the exhaust port of the dry apparatus main body via a return passage, exhaust gas after dry treatment from the drying apparatus main body being circulated and recycled between the drying apparatus main body and the ejector, by a fluid energy of the high pressure dry gas injected from the injection port of the ejector into the ejector.
According to the preferred embodiment, the high pressure gas generating means, the dehumidifier, the ejector and the heater are connected in series via the gas supply passage in succession from an upstream side.
According to another preferred embodiment, the drying apparatus main body is provided with a second exhaust port, and the second exhaust port is connected with an exhaust pipe for discharging extra exhaust gas after dry treatment from the drying apparatus main body to the outside.
According to another preferred embodiment, the drying apparatus further includes a branch gas supply passage which is diverged from a portion between the dehumidifier and the ejector in the gas supply passage, and the branch gas supply passage is connected to a second supply port formed in the drying apparatus main body.
According to another preferred embodiment, a second heater is arranged on the midway of the branch gas supply passage.
According to another preferred embodiment, the drying apparatus main body comprises a hopper, the first supply port is positioned above the second supply port, the gas supply passage and the branch gas supply passage are individually extended from the first and second supply ports into the hopper like a shape of inverted L-letter, and an outlet opening of the gas supply passage is positioned above an outlet opening of the branch gas supply passage.
According to another preferred embodiment, the ejector includes a suction housing which is formed with a suction chamber in its interior, and has the injection and intake ports and an outlet which communicate with the suction chamber; a diffuser connected to the outlet of the suction housing, and having the discharge port; and an injection pipe which is projected from the injection port into the suction chamber, and is extended toward the outlet of the suction housing.
According to another preferred embodiment, a filter is arranged on the midway of the return passage, and the filter contains an activated carbon as an absorbent.
According to another preferred embodiment, the gas comprises nitrogen gas.
In order to achieve the above objects, the present invention provides a drying apparatus using high pressure gas, comprising: a hopper including a supply port and an exhaust port, and receiving an object to be dried; and a gas supply unit for supplying high pressure dry gas to the drying apparatus main body, the gas supply unit including: a highpressure gas generating means for supplying pressurized gas; a dehumidifier for removing water content of gas; an ejector; a heater for heating gas; and a gas supply passage connecting the high pressure gas generating means, the dehumidifier, the ejector and the heater in series in succession from an upstream side while being connected to the supply port of the hopper, and extending from the supply port into the hopper like a shape of inverted L-letter, and further, supplying controlled high pressure dry gas to the hopper; an injection port of the ejector being connected with an upstream side of the gas supply passage, a discharge port of the ejector being connected with a downstream side of the gas supply passage, an intake port of the ejector being connected to the exhaust port of the hopper via a return
Armstrong Westerman Hattori McLeland & Naughton LLP
Lu Jiping
Ogasahara Minoru
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