Patent Application
20200340193
The present invention relates to surface drying systems. More particularly, the present invention relates to systems used to dry a wet layer of a surface such as existing or newly laid pavement or other material such as concrete before applying a new layer of pavement. The present invention is a movable surface drying apparatus.
Pavement is applied in a plurality of layers. The first layer is applied to an underlying substrate such as prepared and compacted dirt or another substrate material. That first layer is allowed to harden for a period of time before the second layer is applied to it. The first layer must be sufficiently dry in accordance with established regulations before the second layer may be applied to it. One or more additional layers may also be applied, with the same need to have a dry surface before a subsequent layer is applied. It is to be understood that the substrate to which new pavement is applied may also be older pavement material, concrete or another material. The present invention is not limited to applying pavement to existing or new pavement.
Since the pavement is usually out in the environment, it is exposed to moisture such as rain and snow. The contractor tasked with making the roadway must wait for conditions to improve until a pavement layer is dry before applying the next layer. The delay in time can be considerable and is of great expense to all involved, in addition to the delay in opening the roadway for drivers.
One known attempt at accelerating pavement layer drying is to run one or more jet engines adjacent to the roadway with the engine exhaust positioned in the direction of wet pavement layers. That is inefficient and costly, with very little of the engine exhaust energy actually involved in drying the moisture on the pavement. Heating devices such as air knives are also ineffective due to the high volume, low pressure air delivery that they produce. The prior art simply uses more energy than is required by the present invention to generate the drying conditions suitable to prepare an underlying surface for new pavement application.
What is needed is an apparatus that addresses the existing problem of construction delay due to a wet layer of intermediary pavement. The apparatus must be cost efficient to use. It must also be effective at quickly drying pavement. The apparatus must also be movable on pavement so that extended stretches of roadway can be dried.
It is an object of the present invention to provide an apparatus that addresses the existing problem of construction delay due to a wet layer of intermediary pavement. The apparatus must be cost efficient to use. It must also be effective at quickly drying an underlying substrate to which the pavement is to be applied. The apparatus must also be movable on the underlying surface so that extended stretches of substrate such as a roadway can be dried.
The present invention is an apparatus that meets these objectives by focusing drying energy directly onto the surface of a substrate to which a new pavement layer is to be applied. The invention includes a structural frame that is affixed to a wheeled or tracked base that is either manually operated or operated by motor. That is, it may be pushed or pulled manually, it may be pushed or pulled by a motorized vehicle or it may be motorized with controls for forward and backward movement. The width of the frame is selectable and that width may be adjusted as needed to account for variable conditions of the underlying substrate to be dried including obstacles such as underground utility access points but not limited thereto. The frame is also affixed to a housing. The housing is pivotally affixed to the frame so that it may be pivoted to be in close proximity to underlying pavement or pivoted away from the pavement when not in use.
The invention further includes an air delivery system, a heating system and an airflow regulation system. Air is compressed and heated before exiting a set of nozzles that generate an overlapping spray pattern of relatively high pressure and relatively hot air that substantially dries water from underlying pavement. Supplemental low pressure heated air and air venting and interior air flow regulation aid in efficient evaporation and removal of moist air produced by the drying action as the housing is moved along the underlying surface.
The invention provides for efficient and effective drying of wet pavement over a desired width of roadway to substantially reduce the time between pavement layer applications. It does so using high pressure, low volume air delivery rather than the ineffective and inefficient process of low pressure, high volume air delivery of prior surface drying systems. This and other characteristics of the invention are further disclosed in the following detailed description, accompanying drawings and appended claims.
A movable pavement drying apparatus 10 of the present invention is shown in
The housing 12 is arranged to retain therein at least portions of the air deliver system 18, the heating system 20 and the airflow regulation system 22. The housing 12 is shaped to aid in directing heated air to the underlying surface 32 when that underlying surface 32 is wet. The housing 12 is fabricated of one or more materials sufficient to maintain structural integrity of the support and movement of the components of the apparatus 10 and to maintain operational effectiveness at relatively high temperatures of at least 500 deg F. The housing 12 may be fabricated of steel but not limited thereto.
The frame 14 is configured to provide a structural frame for the housing 12, the air delivery system 18, the heating system 20 and the airflow regulation system 22. The frame 14 is further configured to include bar extensions 26 and 28 that are used to couple and decouple the apparatus 10 to and from an apparatus that causes movement of the apparatus, such as a tow vehicle, but not limited thereto. The frame 14 is fabricated of one or more materials sufficient to maintain structural integrity of the housing 12 and movement of the components of the apparatus 10 and to maintain operational effectiveness at relatively high temperatures of at least 500 deg F. The frame 14 may be fabricated of steel but not limited thereto. The frame 14 is arranged to be adjustable in the length and width directions by making its length and width members of a plurality of components that may be moved with respect to one another to adjust for length and width as desired.
The wheels 16 are made of one or more materials sufficient enable rolling movement of the apparatus 10 while in operation and with limited loss of structural integrity over variable conditions of the underlying surface 32 and providing sufficient structural integrity to support at least a portion of the load associated with the components of the apparatus 10. The wheels 16 may be of the type used on paving equipment but not limited thereto.
The air delivery system 18 includes a compressor such as a rotary screw compressor used to compress air that is delivered through tubing 36 to air manifold 38. The tubing 36 is arranged as a coil about a heating pipe 40 to function as a heat exchanger of the heating system 20. The tubing 36 includes an entry port 42 and an exit port 44. The entry port 42 is coupled to an output of the compressor. Compressed air enters the entry port 42 at about atmospheric temperature and a pressure of about 100-150 psi. As the compressed air moves through the tubing 36, it is heated as a result of contact with the heating pipe 40 indirectly through the tubing 36, which is made of a thermally conductive material such as copper but not limited thereto. The compressed air from the compressor is heated to a relatively high temperature of no less than 400 deg F. and exits the exit port 44 at a pressure of about 70-120.
The air manifold 38 includes a manifold entry 46 coupled to the exit port 44 of the tubing 36. The manifold 38 is sized and arranged to extend substantially along an interior width of the housing 12 at an interior wall 48 thereof. The manifold 38 is coupled to a rotatable rod 50 or other means for causing the manifold to be manually or automatically rotated fore and aft within the interior of the housing 12. The rotatable rod 50 extends outside of the housing 12 and is attached to a handle or other coupling to enable its movement in a way that causes rotation of the manifold 38. The manifold 38 is fabricated of a material sufficient to function in the environment where the apparatus 10 is used and to maintain its structural integrity when exposed to hot high pressure air that exits the tubing 36. The manifold 38 may be made of stainless steel, for example.
The manifold 38 includes a plurality of nozzles 52 arranged in a line formation along at least a portion of the length of the manifold 38. The nozzles 52 are spaced, sized and configured to deliver an overlapping spray pattern of exhaust air directly onto the underlying surface 32 at a width substantially equivalent to the width of the housing 12. The selectable width of the housing 12 dictates the width of the exhaust air stream exiting the nozzles 52. Selectable rotation of the manifold 38 permits the user to control the angle at which the exhaust air is delivered to the underlying surface 32 from the nozzles 52. For example, if the manifold 38 is fully rotated rearward, the exhaust air may contact the underlying surface 32 at an angle of about 90 degrees whereas full rotation of the manifold 38 forward causes the exhaust air to contact the underlying surface 32 at an angle of about 45 degrees. The nozzles 52 provide localized concentrated application of heated pressurized air that enables fast and substantially complete water removal at the underlying surface 32 below the housing 12.
The exhaust air exiting the nozzles 52 generates a concentrated pattern of air with high pressure that causes water on the underlying surface 32 to separate into small droplets. The high temperature of that exhaust air then evaporates the small water droplets. This water separation and evaporation occurs substantially instantaneously dependent on the depth of the water on the underlying surface 32. It is possible to repeat the process of moving the apparatus 10 on the underlying surface 32 until it can be confirmed that the underlying surface 32 is sufficiently dry to permit application of a layer of pavement material thereon.
The heating system 18 includes the heating pipe 40 or another form of heat exchange element that can be used to heat the compressed air in the tubing 36. The heating system 18 further includes a heat generating apparatus such as a burner 54. The burner 54 may be powered by system voltage of a vehicle employed to tow the apparatus 10 or from another source. The burner 54 may also have a self-contained power supply. An example of a suitable burner is the Model Beckitt AFG burner available from F. W. Webb of South Portland, Me. US, but not limited thereto. The burner 54 is sized and arranged to fit the footprint of the housing 12 at an exterior thereof. The burner 54 may be fueled by oil or gas and is coupled to the heating pipe 40 at pipe entry 58. A fuel source (not shown) used to supply the burner 54 may be located on the tow vehicle 30 or the housing 12.
Combustion occurs within the heating pipe 40, which is made of a thermally conductive material that can withstand the high temperature associated with the flame. The heating pipe 40 may be made of heavy duty steel but is not limited thereto. The heat of the heated heating pipe 40 is transferred to the compressed air in the tubing 36 as noted. The heating pipe 40 includes a pipe exit 60 that transfers exhaust gas from the combustion process into combustion finish chamber 62 of the housing 12 wherein combustion of the fuel source completed. Combustion gas 64 is directed by the interior configuration of the housing 12 onto the underlying surface 32 at a relatively low pressure to warm water on the underlying surface 32 to make it easier to evaporate that water with the exhaust air from the nozzles 52.
The airflow regulation system 22 is arranged to regulate air flow within the interior of the housing 12 while the apparatus 10 is in operation. The airflow regulation system 22 includes a drafting fan 66 and a ducting pipe 68. The drafting fan 66 is attached to the ducting pipe 68. The drafting fan 66 may be variable speed and is employed to aid in maintaining relatively low pressure within the interior of the ducting pipe 68 to promote drafting adjacent to the underlying surface 32 from the front to the rear of the housing 12 through inlet ports 78. The drafting fan 66 may be a Model Dayton 3HMH9 available from Graingers of Portland, Me. US but not limited thereto.
The ducting pipe 68 is positioned aft of the manifold 38 and includes a plurality of inlet ports 78 extending substantially along the width of the ducting pipe 68. Each of the inlet ports 78 includes an adjustable damper 80 to aid in regulating air flow entering the ducting pipe 68 and thereby approximate matching of air flow exhausting from the interior of the housing 12 to inlet airflow to the burner 54 and the compressor. The dampers 80 are installed at the inlet ports 78 to maintain uniform air flow across the underlying surface 32 for the entire width of the housing 12. Inlet ports 78 closest to the drafting fan 66 draw more air than inlet ports 78 spaced away from the drafting fan 66 when all inlet ports 78 are of the same opening size. The use of dampers 80 enable regulation of air flow for uniformity. When all inlet ports 78 are of the same inlet size, air flow aft of the manifold 38 travels toward the inlet ports 78 at the center of the housing 12 closest to drafting fan 66 thereby causing low pressure voids for moisture to linger at the outsides of that air stream. By adjusting the dampers 80 and/or fan speed of the drafting fan 66, it is possible to create a low pressure that is equal across the interior of the ducting pipe 68 thereby creating an equal vacuum effect at all inlet ports 78. This causes the air aft of the manifold 38 to travel straight back to the ducting pipe 68 for immediate extraction. The matching of the inlet to exhaust airflow is part of this tuning of the drafting system. Damper adjustment may be made prior to operation of the apparatus 10 and fine tuning completed by adjusting speed of the drafting fan 66. Optionally, dimensions of the inlet ports 78 may be customized to accomplish the effect of using the dampers 80, such as by making inlet ports 78 nearer the drafting fan 66 smaller than the ones farther from the drafting fan 66.
The apparatus 12 further includes an optional cooling fan 82 deployed through the housing 12 and arranged to regulate temperature of the apparatus as needed during its operation. The cooling fan 82 may be a Model Dayton 3HMJ1 available from Graingers of Portland, Me. US, but not limited thereto. The cooling fan 82 must be sized to enable that temperature regulation as required by the size and performance of the apparatus 10. In operation, the cooling fan 82 cools the components of the apparatus 10 by passing air from the exterior environment into the area between the housing 12 and a housing exterior cover 84, thereby creating a ducted air flow for component cooling. The fan 82 directs heated air from this area onto the underlying surface 32 aft of the duct 68 of the airflow regulation system 22.
When the apparatus 10 is operating, hot compressed air is expelled from the nozzles 52 in the manifold 38 while hot air and exhaust are created in the finish combustion chamber 62. The selectable angle of the nozzles 52 may be directed slightly rearward within the housing 12 and the hot air and exhaust are drawn into the compressed air stream from the finish combustion chamber 62 thereby creating a draft. The mixture of superheated air along with the high concentrated force of the compressed air cause the water to divide into droplets on the underlying surface 32 and evaporate. The air velocity across the adjacent surface increases between the compressed air nozzles 52 and the drafting duct 68. The velocity and high temperature cause any moisture droplets that have not already evaporated to remain suspended and enter the drafting duct 68 to be exhausted by the drafting fan 66.
As noted, the adjustable drafting dampers 80 and fan speed are adjusted to maintain a lower pressure in the duct 68 in order to maintain an even draft across the width of the housing 12. They can also be used to control how much draft is under the housing 12. If there is too much draft, cooler air will be drawn in from the sides of the housing 12. Not enough draft will not expel the moisture at the rate it is being evaporated. The cooling fan 82 aids in resolving this by exhausting warmed air onto the underlying surface 32 behind the drafting duct 68 and help achieve slightly higher drying speeds. The apparatus is of a modular design and can be built to different housing widths and with multiple housings joined together in parallel with one or more sources of fuel and power arranged to operate a plurality of coupled systems.
The present invention has been described with respect to a specific example embodiment. Nevertheless, it is to be understood that various modifications may be made without departing from the spirit and scope of the invention as described by the following claims.
