Drying and gas or vapor contact with solids – Apparatus – With means to treat gas or vapor
Reexamination Certificate
2000-09-01
2002-04-16
Walberg, Teresa (Department: 3742)
Drying and gas or vapor contact with solids
Apparatus
With means to treat gas or vapor
C034S396000, C034S518000, C034S218000, C034S508000
Reexamination Certificate
active
06370792
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to kiln systems and, more particularly, to the introducing of heated air into a kiln chamber for drying lumber.
BACKGROUND OF THE INVENTION
Lumber which has recently been cut contains a relatively large percentage of water and is referred to as green lumber. Prior to being used in applications that demand good grades of lumber, the green lumber must be dried. Drying removes a large amount of water from the lumber and significantly reduces the potential for the lumber to become warped or cracked. Although lumber may be dried in the ambient air, kiln drying accelerates and provides increased control over the drying process.
FIG. 1
illustrates aspects of one type of conventional kiln system
20
. The conventional kiln system
20
includes a kiln chamber
22
that receives a charge of lumber. The charge of lumber typically consists of two or more rectangular stacks of lumber
24
. The kiln chamber
22
is a generally rectangular building that can be at least partially sealed to control the amount of air that is introduced to and exhausted from the kiln chamber. Hot air from a furnace
26
is forced through an inlet duct
28
to a plenum
30
that is positioned in an upper portion of the kiln chamber
22
. The hot air is discharged from the plenum
30
to the interior of the kiln chamber
22
through multiple outlets
32
defined in the top panel of the plenum. Only a few of the outlets
32
are identified by their reference numeral in FIG.
1
. The heated air supplied to the interior of the kiln chamber
22
is circulated by reversible fans
34
so that the heated air flows along a recirculating flow path that extends through the charge of lumber, during which time the air dries the lumber. The furnace
26
draws air from the interior of the kiln chamber
22
via a return duct system (not shown).
Whereas conventional kiln systems
20
of the type illustrated in
FIG. 1
are functional, they operate at least somewhat inefficiently. For example, the momentum of the flow along the recirculating flow path is inefficiently sacrificed in order to accelerate the heated air discharged from the outlets
32
of the plenum
30
. As another example, the heated air discharged from the outlets
32
of the plenum
30
is contemporaneously supplied to both the high and low pressure sides of the fans
34
. Since the heated air has a higher specific volume than cooler air, the introduction of heated air on the low pressure side of the fans means that the fans must disadvantageously pass air having a relatively high specific volume, which is inherently less efficient than passing air having a lower specific volume. In addition, it is common in some conventional kiln systems for the heated air introduced into the kiln chamber not to mix well with the air flowing along the recirculating flow path, which can result in uneven and therefore inefficient drying of lumber.
Inefficiencies in kiln systems reduce the speed at which a charge of lumber can be dried, which can be disadvantageous since mill production depends upon the ability to dry lumber at a sufficient rate so that production need not be slowed to allow for the drying process. Inefficiencies in kiln systems also add to the cost of producing quality lumber. Of course it is advantageous to lower the cost of producing quality lumber. Whereas some conventional kiln systems can be characterized as being efficiently operated and able to dry lumber at a sufficient rate, there is always a demand for new kiln systems and kiln-related structures and methods that can be even more efficiently operated, and that facilitate the drying of lumber at a sufficient rate.
SUMMARY OF THE INVENTION
The present invention solves the above and other problems by providing improved structures and methods for introducing heated air into a kiln chamber.
In accordance with one aspect of the present invention, a kiln system includes a kiln chamber defining a chamber interior space, one or more air moving devices capable of circulating air in the chamber interior space along a recirculating flow path, a furnace capable of providing heated air, and a plenum positioned in the kiln chamber and generally separating the chamber interior space into upper and lower portions. The upper portion of the chamber interior space is positioned above the plenum, and the lower portion of the chamber interior space is positioned below the plenum and is for receiving a charge of lumber for drying. The plenum defines a plenum cavity for receiving the heated air from the furnace. The kiln system further includes one or more upright passageways that are operative for efficiently supplying the heated air from the plenum cavity to the upper portion of the chamber interior space. More specifically, each upright passageway is mounted to the plenum and in communication with the plenum cavity so that the upright passageway is capable of receiving heated air from the plenum cavity. Each upright passageway extends into the upper portion of the chamber interior space and includes at least one outlet positioned proximate the recirculating flow path in the upper portion of the chamber interior space. As a result, each upright passageway is capable of providing heated air from the plenum to the recirculating flow path in the upper portion of the chamber interior space via its outlet.
In accordance with one aspect of the present invention, the air moving devices are positioned in the upper portion of the chamber interior space and include impellers defining rotational axes. Preferably the outlets of the upright passageways are proximate hubs of the nearest respective impellers, which advantageously promotes mixing of the heated air discharged by the upright passageways.
In accordance with one aspect of the present invention, the upright passageways are constructed, arranged and operated so that the heated air discharged thereby is introduced proximate the flows being discharged by the air moving devices and in at least generally the same direction as the flows being discharged by the air moving devices. Preferably the heated air is discharged by the upright passageways at a speed that is at least approximately as great as the speed of the flow being discharged by the air moving devices. As a result and advantageously, the momentum of the flow along the recirculating flow path is not sacrificed in order to accelerate the heated air supplied to the chamber interior space by the upright passageways. Most preferably the heated air is discharged from the upright passageways at a speed that is substantially greater than the speed of the flow being discharged by the air moving devices, which advantageously enhances the flow through the air moving devices. In addition, the upright passageways are proximate the air moving devices so that the flow from the outlets advantageously reduces the pressure near the exits of the air moving devices by means of Bernoulli's principle, which also enhances the flow through the air moving devices.
In accordance with one aspect of the present invention, each upright passageway is constructed and arranged so as to minimize its contribution to the resistance to flow along the recirculating flow path. For each upright passageway, a first cross-dimension is generally perpendicular to the length of the upright passageway and parallel to the portion of the flow path into which the upright passageway extends, and a second cross-dimension is generally perpendicular to both the length of the upright passageway and the portion of the flow path into which the upright passageway extends. The second cross-dimension is less than the first cross-dimension, whereby the upright passageway advantageously defines a low profile with respect to the portion of the recirculating flow path into which the upright passageway extends.
In accordance with one aspect of the present invention, each air moving device is capable of operating in clockwise and counterclockwise modes. Flow along the recirculating flow path travels clockwise while the
Culp George R.
Nagel Robert T.
Alston & Bird LLP
Culp George R.
Dahbour Fadi H.
Walberg Teresa
LandOfFree
Structure and methods for introducing heated ari into a kiln... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Structure and methods for introducing heated ari into a kiln..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Structure and methods for introducing heated ari into a kiln... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2925098