Patent Application
20100012298
The present invention relates a process and system for heat recovery and pressure control.
Animal byproduct meals, fecal material, agricultural fertilizer, corn byproducts, wheat byproducts, wood pulp, and the like are high moisture content materials that may provide a rich source of energy when effectively dehydrated. Further, some of this material should be sterilized and deodorized before being discharged into the environment. These materials must be dried to about 5% moisture to be a high grade fuel. A large quantity of high temperature air is required to evaporate the moisture from the material, and the air may become contaminated with odors and pathogens from the material. A great deal of energy is required to heat the large quantity of air required. Further, the pressure of the air must be maintained at a suitable pressure.
Therefore, there is a need for a process and system for heat recovery and pressure control.
An embodiment of the present invention provides a system for heat recovery and pressure control. The system includes: a fresh air heat exchanger including a fresh air inlet, at least one fresh air heat exchanger conduit, and a fresh air outlet; a pre-heater heat exchanger including a pre-heater inlet, at least one pre-heater heat exchanger conduit, and a pre-heater outlet; and a proportioning valve coupled to the at least one fresh air heat exchanger conduit and the at least one pre-heater heat exchanger conduit, the proportioning valve including: a valve plate. The fresh air heat exchanger is adapted to receive fresh air in the fresh air inlet, warm the fresh air by transferring heat from the at least one fresh air heat exchanger conduit, and transmit the warmed fresh air through the fresh air outlet. The pre-heater heat exchanger is adapted to receive contaminated air in the pre-heater inlet, pre-heat the contaminated air by transferring heat from the at least one pre-heater heat exchanger conduit, and transmit the pre-heated contaminated air through the pre-heater outlet. The at least one fresh air heat exchanger conduit and the at least one pre-heater heat exchanger conduit are adapted to receive hot air and transfer the heat from the hot air. The proportioning valve is adapted to control a flow of the hot air through the at least one fresh air heat exchanger conduit and the at least one pre-heater heat exchanger conduit.
At least one of the fresh air heat exchanger further or the pre-heater heat exchanger may include at least one baffle and at least two passes, wherein the baffle is adapted to increase a length of a path that the air travels through the heat exchanger by guiding the air through the at least two passes.
The at least one of the fresh air heat exchanger or the pre-heater heat exchanger may further include a gap between the at least one heat exchanger conduit and an interior wall of the heat exchanger.
The system may further include an expansion box adapted to receive hot air and transmit the hot air to the at least one fresh air heat exchanger conduit and the at least one pre-heater heat exchanger conduit in accordance with pressures in the at least one fresh air heat exchanger conduit and the at least one pre-heater heat exchanger conduit.
The proportioning valve may be further adapted to be controlled based upon at least one of the temperatures of the fresh air exiting the fresh air heat exchanger or the temperature of the contaminated air exiting the pre-heater heat exchanger in accordance with a measurement of a temperature of the fresh air or a measurement of a temperature of the contaminated air.
At least one of the fresh air heat exchanger and the pre-heater heat exchanger may further include a heat exchanger conduit plate attached to an end of the at least one heat exchanger conduit and adapted to receive at least one gasket around a perimeter of the heat exchanger conduit plate so that an air-tight seal is maintained between the heat exchanger conduit plate and an interior wall of the heat exchanger as the heat exchanger conduit plate moves along the interior wall of the heat exchanger in accordance with an increase or decrease in a length of the at least one heat exchanger conduit.
Another embodiment of the present invention provides a method for heat recovery and pressure control. The method includes: receiving fresh air in a fresh air inlet of a fresh air heat exchanger, warming the fresh air by transferring heat from at least one fresh air heat exchanger conduit, and transmitting the warmed fresh air through a fresh air outlet; receiving contaminated air in a pre-heater inlet of a pre-heater heat exchanger, pre-heating the contaminated air by transferring heat from at least one pre-heater heat exchanger conduit, and transmitting the pre-heated contaminated air through a pre-heater outlet; receiving hot air in the at least one fresh air heat exchanger conduit and the at least one pre-heater heat exchanger conduit and transferring the heat from the hot air; and controlling the flow of the hot air through the at least one fresh air heat exchanger conduit and the at least one pre-heater heat exchanger conduit by adjusting a proportioning valve.
The method may further include guiding the air around at least one baffle and through at least two passes in at least one of the fresh air heat exchanger and the pre-heater heat exchanger so that a length of a path traveled by the air is increased.
The method may further include passing the air through a gap between at least one of the at least one fresh air heat exchanger conduit and an interior wall of the fresh air heat exchanger, and the at least one pre-heater heat exchanger conduit and an interior wall of the pre-heater heat exchanger.
The method may further include receiving the hot air in an expansion box and transmitting the hot air to the at least one fresh air heat exchanger conduit and the at least one pre-heater heat exchanger conduit in accordance with pressures in the at least one fresh air heat exchanger conduit and the at least one pre-heater heat exchanger conduit.
The method may further include controlling the temperature of the fresh air exiting the fresh air heat exchanger and the temperature of the contaminated air exiting the pre-heater heat exchanger by adjusting the proportioning valve.
The method may further include maintaining an air-tight seal between at least one of a fresh air heat exchanger conduit plate and an interior wall of the fresh air heat exchanger, and a pre-heater heat exchanger conduit plate and an interior wall of the pre-heater heat exchanger, as the heat exchanger conduit plate moves along the interior wall of the heat exchanger in accordance with an increase or decrease in a length of the at least one heat exchanger conduit.
Another embodiment of the present invention provides a system for heat recovery and pressure control. The system includes: a heat exchanger including an air inlet; at least one heat exchanger conduit; a heat exchanger conduit plate attached to an end of the at least one heat exchanger conduit and adapted to receive at least one gasket around a perimeter of the heat exchanger conduit plate; and an air outlet. An air-tight seal is maintained between the heat exchanger conduit plate and an interior wall of the heat exchanger as the heat exchanger conduit plate moves along the interior wall of the heat exchanger in accordance with an increase or decrease in a length of the at least one heat exchanger conduit.
The heat exchanger may further include at least one baffle and at least two passes, wherein the baffle is adapted to increase a length of a path that the air travels through the heat exchanger by guiding the air through the at least two passes.
The heat exchanger may further include a gap between the at least one heat exchanger conduit and an interior wall of the heat exchanger.
The system may further include an expansion box adapted to receive hot air and transmit the hot air to the at least one heat exchanger conduit in accordance with a pressure in the at least one air heat exchanger conduit.
The system may further include a proportioning valve adapted to control the temperature of the air exiting the heat exchanger.
Another embodiment of the present invention provides a method for heat recovery and pressure control. The method includes: receiving air in an air inlet of a heat exchanger, warming the air by transferring heat from at least one heat exchanger conduit, and transmitting the warmed air through the air outlet; receiving hot air in the at least one heat exchanger conduit and transferring the heat from the hot air. The heat exchanger includes a heat exchanger conduit plate attached to an end of the at least one heat exchanger conduit and adapted to receive at least one gasket around a perimeter of the heat exchanger conduit plate so that an air-tight seal is maintained between the heat exchanger conduit plate and an interior wall of the heat exchanger as the heat exchanger conduit plate moves along the interior wall of the heat exchanger in accordance with an increase or decrease in a length of the at least one heat exchanger conduit.
The method may further include guiding the air around at least one baffle and through at least two passes in the heat exchanger so that a length of a path traveled by the air is increased.
The method may further include passing the air through a gap between the at least one exchanger conduit and an interior wall of the heat exchanger so that the air expands in the gap.
The detailed description set forth below in connection with the drawings is intended as a description of embodiments of a process and system for heat recovery and pressure control in accordance with the present invention and is not intended to represent the only forms in which the invention may be constructed or utilized. It is to be understood that the same or equivalent functions and structures may be accomplished by different embodiments that are also intended to be encompassed within the spirit and scope of the invention. As denoted elsewhere herein, like element numbers indicate like elements or features.
Material that must be dried to be a high grade fuel requires a large quantity of high temperature air to evaporate the moisture from the material, and the air may become contaminated with odors and pathogens from the material. Since a great deal of energy is necessary to heat the large quantity of air required, a system and process for capturing and reusing some of this energy would make the processing of this material more efficient. Further, the pressure of the air throughout the processing of the material should be maintained at a suitable pressure.
A process according to an embodiment of the present invention as shown in
The pre-heated contaminated air passes to a chamber to be heated 130. Here, for example, the chamber, such as a heating detoxification chamber, heats the contaminated air to a sufficient temperature to sterilize and deodorize the air.
The hot chamber discharge air passes back to the heat recovery and pressure control unit to be utilized to pre-heat contaminated air entering the chamber and warm fresh air entering the processor 140. Because the chamber discharge air has already been heated, e.g., sterilized and deodorized, the chamber discharge air is contained away from the contaminated air and the fresh air.
A system for heat recovery and pressure control according to an embodiment of the invention as shown in
Here, fresh air enters the fresh air heat exchanger 14 through a fresh air inlet 32. For example, a fresh air fan 12 may blow fresh air into the fresh air heat exchanger 14. The fresh air passes through the fresh air heat exchanger 14, where the fresh air is warmed, and exits the fresh air heat exchanger through a fresh air outlet 26.
In an embodiment of the present invention as shown in
In an embodiment of the present invention, the fresh air passes around a number of or series of (e.g., six) fresh air baffles, which will form multiple (e.g., seven cross) passes for the fresh air.
In an embodiment of the present invention, the fresh air is warmed to a temperature in a range from about 600 degrees C. to about 650 degrees C.
In an embodiment of the present invention, the fresh air then passes into a processor where the fresh air is utilized to remove moisture from a material. Here, the fresh air may become contaminated by the material.
The contaminated air is returned to the system and passes into the pre-heater heat exchanger 16 through a pre-heater inlet 34. For example, a contaminated air fan 10 may blow the contaminated air into the pre-heater heat exchanger 16. The contaminated air passes through the pre-heater heat exchanger 16, where the contaminated air is pre-heated, and exits the pre-heater heat exchanger through a pre-heater outlet 28. However, because the contaminated air is contaminated, the contaminated air is contained away from the fresh air so that the fresh air is not contaminated.
In an embodiment of the present invention as shown in
In an embodiment of the present invention, the contaminated air passes around a number of or series of (e.g., six) fresh air baffles, which will form multiple (e.g., seven) cross passes for the contaminated air.
In an embodiment of the present invention, the contaminated air enters the pre-heater heat exchanger 16 at a temperature of about 120 degrees C. and is pre-heated to a temperature of about 450 degrees C.
In an embodiment of the present invention, the heat exchangers are formed of a corrosion-resistant and heat-resistant material (e.g., stainless steel).
In an embodiment of the present invention, the contaminated air then passes into a chamber, such as a heating detoxification chamber, where the contaminated air is heated. For example, the contaminated air may be heated to a high enough temperature (or so that the contaminated air is hot enough) to sterilize and deodorize the air, e.g., a temperature in a range from about 800 degrees C. to about 850 degrees C.
The hot air passes back to the system through a conduit 30 and into an expansion box 25. Here, the hot air is allowed to enter either at least one fresh air heat exchanger tube (or suitable conduit) 70 or at least one pre-heater heat exchanger tube 72, in accordance with the pressure in the at least one fresh air heat exchanger tube (or suitable conduit) 70 and the at least one pre-heater heat exchanger tube 72.
The at least one fresh air heat exchanger tube 70 is mounted in and sealed to a fresh air hot end tube plate 50 at the expansion box 25. The at least one pre-heater heat exchange tube 72 is mounted in and sealed to a pre-heater hot end tube plate 52 at the expansion box 25, as shown in
The other end of the at least one fresh air heat exchanger tube 70 is mounted in and sealed to a fresh air cold end tube plate 80, as shown in
In an embodiment of the present invention, the tubes 70 and 72 may expand as hot air is transported through the tubes 70 and 72. As the tubes 70 and 72 expand, the length of the tubes 70 and 72 increase. For example, tubes 70 and 72 that are about six meters long may expand about 40 mm in length. Here, the lengthening of the tubes 70 and 72 may be accommodated in the heat exchangers 14 and 16 while maintaining the containment of the fresh air and the contaminated air away from the hot air. As shown in
In an embodiment of the present invention, the tubes 70 and 72 are welded to the tube plates 50, 52, 80, and 82.
In an embodiment of the present invention, the tubes 70 and 72 have a diameter of about ¾ inch.
In an embodiment of the present invention, the tubes 70 and 72 are about six meters long.
In an embodiment of the present invention, the tubes 70 and 72 are formed of stainless steel so that the tubes 70, 72 can withstand high temperatures and may expand or contract as the tubes 70 and 72 are heated or cooled.
In an embodiment of the present invention, the system has a nest (e.g., about 1500) of fresh air heat exchanger tubes 70 and a nest (e.g., 1500) of pre-heater heat exchanger tubes 72, with sufficient surface area to carry out the heat recuperation requirement. For example in an embodiment with a series of baffles, to counter a high pressure drop of the cross passes, a gap (or expansion chamber) between the sides of the tubes 70 and 72 and the sides of the heat exchanger 14, 16 may allow the air moving through the heat exchanger 14, 16 to expand and drop in velocity to obtain static regain, thus providing a more uniform air mix to the air moving over the next pass. Therefore, there is a lower total pressure drop as the air travels through the heat exchanger 14, 16, and there is a more stable mass flow.
In an embodiment of the present invention, the tubes 70 and 72 are mounted about 5 mm apart.
In an embodiment of the present invention, the temperature of the hot air entering the at least one fresh air heat exchanger tube and the at least one pre-heater heat exchanger tube is a temperature in a range from about 800 degrees C. to about 850 degrees C.
The interior of the at least one fresh air heat exchanger tube 70 opens into a manifold that is coupled to conduit 22, and the interior of the at least one pre-heater heat exchanger tube 72 opens into a second manifold that is coupled to conduit 24. As shown in
In another example, the valve plate 90 may be rotated so that the opening from the conduit 24 to exit 20 is decreased and the opening from conduit 22 to exit 20 is increased. The pressure in the at least one pre-heater heat exchanger tube 72 will be increased, and the pressure in the at least one fresh air heat exchanger tube 70 will be decreased. As a result, less hot air enters the at least one pre-heater heat exchanger tube 72 and more hot air enters the at least one fresh air heat exchanger tube 70. Therefore, less heat is transferred to the contaminated air in the pre-heater heat exchanger 16 so the temperature of the pre-heated contaminated air decreases, and more heat is transferred to the fresh air in the fresh air heat exchanger 14 so the temperature of the warmed fresh air increases.
Here, the valve plate 90 may be controlled to maintain a suitable temperature of the warmed fresh air and or the pre-heated contaminated air. For example, the temperature of the pre-heated contaminated air may be measured, and the valve plate 90 may be adjusted accordingly. Thus, if the temperature of the pre-heated contaminated air is too low, then the valve plate 90 is rotated so that the opening from the conduit 24 is increased so that more heat is transferred to the contaminated air, as described above. Therefore, the temperature of the contaminated air increases. Alternatively, if the temperature of the contaminated air is too high, then the valve plate 90 is rotated so that the opening from the conduit 24 is decreased so that less heat is transferred to the contaminated air, as described above. Therefore, the temperature of the contaminated air decreases.
In another example, the temperature of the warmed fresh air may be measured, and the valve plate 90 may be adjusted accordingly. Thus, if the temperature of the warmed fresh air is too low, then the valve plate 90 is rotated so that the opening from the conduit 22 is increased so that more heat is transferred to the fresh air, as described above. Therefore, the temperature of fresh air increases. Alternatively, if the temperature of the fresh air is too high, then the valve plate 90 is rotated so that the opening from the conduit 22 is decreased so that less heat is transferred to the fresh air, as described above. Therefore, the temperature of the fresh air decreases.
In an embodiment of the present invention, the valve plate 90 may be controlled by an automated process.
In an embodiment of the present invention, the temperatures of the fresh air, the contaminated air, and the hot air may be measured at any suitable location, e.g., any suitable location where the air is transferred.
In another embodiment of the present invention, the temperature of the hot air may be adjusted in accordance with a measurement of the temperature of the fresh air and/or the contaminated air.
In an embodiment of the present invention, the air leaving the tubes 70 and 72 is about 120 degrees C.
In an embodiment of the present invention, the velocity of the air leaving the exit 20 is about 5000 feet per minute.
Although the present invention has been described through the use of exemplary embodiments, it will be appreciated by those of skill in the art that various modifications may be made to the described embodiments that fall within the scope and spirit of the invention as defined by the claims and their equivalents appended hereto. For example, aspects shown above with particular embodiments may be combined with or incorporated into other embodiments.
This application claims priority to and the benefit of U.S. Provisional Patent Application No. 61/080,466, filed on Jul. 14, 2008, in the United States Patent and Trademark Office, the entire content of which is incorporated herein by reference. The entire content of United States patent applications PROCESS AND APPARATUS FOR DRYING AND POWDERIZING MATERIAL (Attorney Docket No: T643-64003; application Ser. No. ______), ENERGY RECOVERY AND TRANSFER SYSTEM AND PROCESS (Attorney Docket No: T643-63990; application Ser. No. ______), and METHOD AND APPARATUS FOR STERILIZING AND DEODORIZING AIR (Attorney Docket No: T643-64005; application Ser. No. ______) filed on Jul. 14, 2009 in the United States Patent and Trademark Office is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61080466 | Jul 2008 | US |
