Drying and gas or vapor contact with solids – Apparatus – With fluid current conveying of treated material
Reexamination Certificate
1999-10-20
2001-08-07
Gravini, Stephen (Department: 3749)
Drying and gas or vapor contact with solids
Apparatus
With fluid current conveying of treated material
C034S583000
Reexamination Certificate
active
06269553
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a drying apparatus for the drying of bulk material, more particularly synthetic resin granules or powder.
It is more especially in the synthetic resin processing industry that it is frequently necessary for raw materials in the form of granules, powder or in a similar bulk condition to be dried, before same are for example processed in an injection molding machine or in an extruder. For this purpose hot gas driers are known, in the case of which the gas employed for drying is heated prior to the drying operation to a temperature specific to the synthetic resin and the hot gas is then passed through the material to be dried.
In order to ensure effective drying of the material to be dried on the one hand while at the same time avoiding unnecessary waste of energy on the other hand it is necessary to hold the drying gas flowing through the material at a predetermined temperature within the drying container. For this purpose switching and regulating means are known, which find the temperature at the outlet of the drying container by means of a temperature sensor, which is connected by means of a capillary tube connection with a thermostat (or flow rate control valve) arranged in the gas supply duct. In the event of the temperature increasing at the outlet of the drying container, for example because a trouble condition has occurred, and the heated synthetic resin material is no longer removed from the drying container, the thermostat reduces the passage of gas to the drying container. If the gas outlet temperature falls below a predetermined value, the gas volume flow rate to the drying container will be increased.
It is however a disadvantage in this respect that thermostat-operated valves capable of operating precisely are extremely expensive and consequently do not come into question for small drying plant. In the case of known drying plant use is consequently usually made of cheap but extremely inaccurate thermostat-driven valves for volume flow rate regulation of the drying gas. A further disadvantage is that thermostat-operated regulation valves, which are connected via a capillary tube connection with the temperature sensor, respond with a long time lag to changes in temperature. A rapid correction of the gas volume flow rate is therefore not possible. More particularly in the case of small drying gas volume flow rates of below 1000 1/min the known thermostat regulation means react slowly and thus lead to inaccurate process control. A still further disadvantage is that using conventional thermostat regulation means it is not possible to select any drying gas flows specific to the material to be dried, i.e. to use different drying programs, as they are for example necessary of different types of synthetic resin, such as ABS or PET.
SUMMARY OF THE INVENTION
Accordingly one object of the invention is to provide a drying apparatus of the type initially mentioned, with which the rate of the drying gas volume flow to be introduced into the drying container may be set in an extremely accurate, rapid and furthermore simple and economic manner.
In accordance with the invention the volume flow rate setting means comprises at least two flow off/on means which are arranged in at least two parallel-connected branch duct of the gas supply ducts are able to be switched over by the switching and regulation means between an opened and a closed position so that the drying gas volume flow introduced into the receiving space is set by the number and/or selection of the opened flow off/on means.
The drying apparatus in accordance with the invention preferably comprises a multi-duct intermediate member in the gas supply duct, there being a flow off/on means, for example in the form of a solenoid valve, arranged in each branch duct. These flow off/on means are only able to be switched over between an opened and a closed position and may hence be extremely simple in design and therefore low in price. The volume flow rate of the drying gas introduced into the drying container accordingly is set by how many and/or which of these flow off/on means are opened. A further way of varying the volume flow is due to the fact that flow through off/on means in accordance with an advantageous embodiment of the invention have through flow openings or lumens of different size. If for instance four parallel-connected solenoid valves with different sizes of flow through opening are used it is possible have 15 different switching combinations to produce 15 different drying gas volume flow rates (beside the zero flow rate, for which all valves are closed).
In lieu of solenoid valves it is possible as well to design the flow off/on means in some other manner, for example in the form of sliding plates or gate valve
An other preferred feature of the invention is such that the switching and regulation means is mounted together with the through flow off/on means in a removable manner on the drying container. This offers the advantage that different drying containers, which are best suited for certain materials, may be combined with a predetermined switching and regulation means.
In accordance with a further preferred development of the invention different drying programs are stored in the switching and regulation means, with which programs predetermined combinations of opened and closed flow through off/on means may be selected. This offers the advantage that for different materials to be dried, and more especially for different sorts of synthetic resin, specific optimally adapted volume flow rate programs may be run.
REFERENCES:
patent: 3600818 (1971-08-01), Lang
patent: 3818606 (1974-06-01), Marcellini
patent: 4349969 (1982-09-01), Stewart et al.
patent: 4413426 (1983-11-01), Graff
patent: 4509272 (1985-04-01), Graff
patent: 4561192 (1985-12-01), Meade
patent: 4606896 (1986-08-01), Kita et al.
patent: 4628831 (1986-12-01), Delessard et al.
patent: 5391356 (1995-02-01), Thorman
patent: 5420404 (1995-05-01), Goodman et al.
patent: 5513445 (1996-05-01), Farrag
patent: 5566468 (1996-10-01), Graeff
patent: 6058623 (2000-05-01), Brooks et al.
patent: 33 20 978 A1 (1983-12-01), None
patent: 3131471 (1990-06-01), None
patent: 43 00 595 A1 (1994-07-01), None
patent: 296 21 313 U1 (1997-03-01), None
patent: 0 061 161 (1985-07-01), None
patent: 2 122 384 (1984-01-01), None
Brochure; Motan Trockner; p. 4;1979.
Brochure; Drying With Motan; Motan Plast-Automation: Everything for Commercial Efficiency in Technical Plastic Production; p. 4; 1983.
Gravini Stephen
Nixon & Vanderhye PC
Wilheim Klaus
LandOfFree
Drying apparatus for the drying of bulk material does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Drying apparatus for the drying of bulk material, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Drying apparatus for the drying of bulk material will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2443112