Patent Application
20090265952
The present invention relates to crop material dryers, and more specifically to crop material dryers deployable in the field.
In recent years, farmers around the globe have been collecting harvested crop material, such as grain, in large plastic silo bags or sacks directly in the field during the harvesting process. By collecting in this manner, the time consuming process of transporting the crop material to bin storage or elevators during the critical time of harvesting is minimized. This makes available man power to be focused solely on the process of harvesting the crop material in the field. Once in the bags the crop material may be collected later after the harvesting is complete, usually bringing a more favorable price.
One problem with this approach to collecting crop material is that there is limited ability to dry the crop material. The silo bags must be rugged enough and impervious to resist infiltration by rodents and other scavengers so that the bags do not have adequate natural porosity to enable air flow from the ambient air to dry. Furthermore, the crop material cannot be excessively high in moisture or it can spoil before retrieval. This makes the application of field bagging limited to more arid climates where rain damage is less likely or less frequent. The need for the crop material to be very dry for silo bags severely limits the time the farmer can wait until the crop material is dry enough before he can begin harvesting.
What is needed in the art therefore is an effective way to dry crop material in collection devices deployed in the field for harvested crop material.
In one form, the invention is a portable in situ crop material dryer including a chamber deployable in a field for harvested crop material and an internal combustion engine providing a rotary output. An air movement device is coupled to and driven by the rotary output of the combustion engine. The heat exchange device receives a heat input from the combustion engine, the heat exchange device being in series flow connection with the air movement device. The air movement device is removeably fluidly coupled to the chamber for directing heated air through the chamber for drying harvested crop material.
In another form, the invention is a portable system for providing a flow of heated air in situ for drying harvested crop material. The system includes a frame and a combustion engine mounted on the frame and providing a rotary output to an air movement device coupled to and driven by the rotary output of the combustion engine. A heat exchange device mounted on the frame receives a heat input from the combustion engine, the heat exchange device being in series flow connection with the air movement device to increase the temperature of the air therethrough. Finally, an air outlet receives the air flow and the air outlet is removeably connectable to dry harvested crop material.
Referring to
In accordance with the present invention a crop material drying unit, generally indicated by reference character 16, is incorporated with the harvest bag 10. The crop material drying unit 16 is shown as a portable unit for deployment in the field in situ and to that end has a trailer 18, ground wheels 20 and a hitch 22 for connecting to a truck or tractor. The crop material drying unit 16 has an outlet 24 removeably connected to one end 26 of the harvest bag 10. It should be apparent to those skilled in the art that an appropriate means for sealing the end 26 of bag 10 onto the outlet 24 would be employed. The crop material drying unit 16 has an ambient air inlet 28 where air passes under a rain cover 30 to dryer inlet 32. The air thus directed from inlet 28 to outlet 24 passes across the crop material 12 to a bag outlet 34, also having a rain cover 36 for discharge to the atmosphere. Appropriate support brackets 38 support a far end 40 of the harvest bag 10 in a vertical position so as to take advantage of the rain cover 36. It should be apparent to those skilled in the art, however, that the bag outlet 34 may be oriented other than strictly in a vertical position.
The air movement device 42 is driven by a combustion engine 44 providing a rotary mechanical output shown by dashed lines 46 to the air movement device 42. Combustion engine 44 may take a number of forms but they all involve an air breathing, fuel consuming, engine in which a fuel supply 46 is connected to combustion engine 44 by an appropriate fuel line 48. Major types of combustion engines are two cycle or four cycle reciprocating piston engines. Such engines may be spark ignited with a gasoline fuel supply or may be compression ignition ignited using the heat of compression to ignite a timed and metered diesel fuel charge in the engine combustion chambers (not shown). Although a compression ignition engine is suitable for use in the dryer 16, a spark ignition engine is preferable because it has a greater waste heat rejection to be utilized as discussed below.
A heat exchange device 50 is interconnected with the combustion engine 40 by a connection indicated by line 52. Heat exchange device 50 has a first path that is in heat exchange flow relationship to air discharged from the air movement device 42 through line 54 for heating the air to an elevated temperature and discharging it through line 56. In one form, the heat exchange device is a cooling system for the combustion engine 44. In the instance when combustion engine 44 is a liquid cooled engine, the heat exchange device 50 receives liquid coolant that is circulated from combustion engine 44 by an internal pump (not shown) and the heat exchange device 50 is a liquid to air heat exchanger. This means that the heat rejected by the combustion engine 44 is given up to the air passing through the heat exchange device 50 to provide a significant increase in temperature.
In the case where the combustion engine 44 is an air cooled engine, the heat exchange device 50 may take the form of an air to air heat exchanger in which air is directed across a finned outer housing for the engine combustion cylinder and the heat given up to the air passing through. In this case it would be appropriate to utilize the air movement device 42 to direct air over the fins in the heat exchange device 50 to also significantly increase the temperature of the air directed through the heat exchange device 50.
The engines described above are reciprocating internal combustion engines. It should also be noted that gas turbines may be utilized and in this case the heat exchange device would also be an air to air heat exchange device for increasing temperature of the air through line 56.
A burner 58 may optionally be employed in line 56 between heat exchange device 50 and outlet 24 to further increase temperature of the air thus discharged. Furthermore, an electrical generator 60 may be employed to be driven by combustion engine 44 through mechanical connection 62 to provide auxiliary electrical lighting and other power. It should be noted that with the additional load provided by the electrical generator, additional waste heat is generated in the heat exchange device 50 to further increase the temperature of the air flow from outlet 24.
The heated air is thus passed over the crop material 12 in harvest bag 10 and out the bag outlet 34. By heating the air passing across the crop material, the moisture of the crop material is decreased to the point where it becomes substantially more storeable for delivery to a bin, biomass facility or other processor.
In operation, the crop material dryer 16 is towed by an appropriate tractor or truck to a harvest bag 10 having crop material 12 already in it. The harvest bag 10 is purposely arranged so that some air space is available along the top of the harvest bag 10 so as to promote adequate air flow. The outlet of crop material dryer 16 is removeably connected to inlet end 26 of harvest bag 10 and the bag outlet 34 is deployed at the opposite end 40. The combustion engine 44 is operated and heated air flows through the harvest bag 10 and across the crop material 12. The increase in temperature lowers the humidity of the crop material. The crop material dryer 16 is self-contained and can be operated continuously and through the night until the moisture content of the crop material is at a sufficiently low level. The use of the electrical generator 60 allows operation at night. In addition the increased load imposed by the electrical generator 60 increases the waste heat of combustion engine which in turn increases the amount of heat delivered to the air through heat exchange device 50. When the crop material has reached a sufficiently low humidity level, the outlet 24 is removed from inlet 26 and bag outlet 34 is also removed. The harvest bag 10 may then be sealed for appropriate collection for delivery to a crop material silo or other collection means.
Having described the preferred embodiment, it will become apparent that various modifications can be made without departing from the scope of the invention as defined in the accompanying claims.
