Patent Application
20230151560
The present technology is related to producing asphalt using exhaust from a generator. More specifically, this technology relates to producing hot mix asphalt from virgin aggregate (aggregate), liquid asphalt, additives, and up to 100% recycle material (combined as ‘asphalt materials’) using exhaust from a generator that provides electrical power for onsite use or to a power grid.
Hot mix asphalt plants according to the conventional art utilize an open flame burner to produce heat for drying aggregates. Excess heat is vented to the atmosphere. The open flame burner is typically a large fossil fuel burner attached to the end of a rotary dryer drum. The drum lifts the aggregate material and veils it across the heat stream of the burner to reduce the moisture content and raise the temperature of the aggregate material, which is necessary to produce hot mix asphalt. Exhaust leaves the dryer through a duct and is filtered to remove dust in the air stream.
Conventional hot mix asphalt plants suffer from poor efficiency and high emissions. There have been many efforts to fine tune hot mix asphalt plants for improvement in these areas, but none have been very successful. Aggregate must be super-heated in order to drive the moisture out of recycle which limits the amount of recycled asphalt product (RAP) and recycled asphalt shingles (RAS) that may be incorporated into the mixture. In addition, the conventional hot mix asphalt plants can only handle a narrow range of recycled content because of difficulties associated with adjusting the plant. For example, the dryer drum in a conventional hot mix asphalt plant needs to be re-flighted when substantially changing the percentage of recycled content to balance the heat of the virgin aggregate and RAP to meet the temperature target of the finished product.
Accordingly, some embodiments of the present disclosure relate to a system for producing hot mix asphalt, the system including a generator having an exhaust port; a dryer drum having an inlet; a duct connecting the exhaust port to the inlet, the duct being configured to convey a first flow of hot gas from the exhaust port; an exhaust bypass vent configured to convey a second flow of hot gas diverging from the first flow of hot gas; and a valve disposed at a junction between the duct and the exhaust bypass vent, the valve being configured to adjust a flow rate of the second flow of hot gas. The dryer drum is configured to produce hot mix asphalt from asphalt materials using a third flow of hot gas diverging from the first flow of hot gas and entering the dryer drum through the inlet.
In some embodiments, the exhaust bypass vent is in fluid communication with atmosphere. In some embodiments, the generator is a gas turbine generator. In some embodiments, the valve is a gate valve. In some embodiments, the dryer drum is further configured to produce the hot mix asphalt by rotating the dryer drum with the asphalt materials inside the dryer drum and the third flow flowing through the dryer drum. In some embodiments, a flow rate of the first flow is equal to the flow rate of the second flow plus a flow rate of the third flow. In some embodiments, the valve is further configured to decrease the flow rate of the third flow by increasing the flow rate of the second flow. In some embodiments, the valve is further configured to increase the flow rate of the third flow by decreasing the flow rate of the second flow.
In some embodiments, the system further includes an air intake structure configured to convey ambient air into the generator. In some embodiments, the asphalt materials include virgin asphalt and recycled asphalt. In some embodiments, the dryer drum is tilted such that a first axial end of the dryer drum is at a lower elevation than a second axial end of the dryer drum. In some embodiments, the inlet is disposed at the first axial end. In some embodiments, the dryer drum further includes an opening at the second axial end for loading the asphalt materials into the dryer drum. In some embodiments, the dryer drum includes an exhaust structure, and an outlet at the second axial end. In some embodiments, the exhaust structure is connected to the outlet. In some embodiments, the third flow flows through the dryer drum, through the outlet, through the exhaust structure, and into a baghouse.
In some embodiments, the system further includes a support structure configured to support the dryer drum, and a drive system configured to axially rotate the dryer drum. In some embodiments, the generator is in electrical communication with a power grid to provide electrical energy to the power grid. In some embodiments, the generator is configured to provide electrical energy to equipment on a manufacturing site including the system.
Some embodiments of the present disclosure relate to a power generation apparatus including a generator having an exhaust port; a dryer drum having an inlet; a duct connecting the exhaust port to the inlet, the duct being configured to convey a first flow of hot gas from the exhaust port; an exhaust bypass vent configured to convey a second flow of hot gas diverging from the first flow of hot gas; and a valve disposed at a junction between the duct and the exhaust bypass vent, the valve being configured to adjust a flow rate of the second flow of hot gas. The dryer drum is configured to produce hot mix asphalt from asphalt materials using a third flow of hot gas diverging from the first flow of hot gas and entering the dryer drum through the inlet. The generator is configured to provide electrical energy to a power grid or equipment on a manufacturing site including the power generation apparatus.
Some embodiments of the present disclosure relate to a method of producing hot mix asphalt and providing electrical energy, the method including providing a generator having an exhaust port; providing a dryer drum having an inlet; providing an exhaust bypass vent; connecting the exhaust port to the inlet using a duct; installing a valve at a junction between the duct and the exhaust bypass vent; running the generator to produce hot gas such that a first flow of the hot gas flows through the duct, the first flow of the hot gas diverging into a second flow of the hot gas and a third flow of the hot gas, the second flow of the hot gas flowing through the exhaust bypass vent, and the third flow of the hot gas flowing through the inlet and into the dryer drum; controlling a flow rate of the third flow of the hot gas by controlling the valve to control a flow rate of the second flow of the hot gas; producing hot mix asphalt from asphalt materials in the dryer drum using the third flow of the hot gas; and providing, to a power grid or to equipment on a manufacturing site having the generator, electrical energy generated by the running of the generator.
In some embodiments, the hot gas is exhaust gas produced by the running of the generator. In some embodiments, the producing of the hot mix asphalt and the providing of the electrical energy to the power grid occur simultaneously.
Additional details and feature of embodiments of the technology will now be described in connection with the following drawings.
The drawings show embodiments of the disclosed subject matter for the purpose of illustrating the invention. However, it should be understood that the present application is not limited to the precise arrangements and instrumentalities shown in the drawings, wherein:
Some embodiments of the present disclosure are directed to a system for producing hot mix asphalt from asphalt materials using exhaust from a generator. As used herein, “hot mix asphalt” refers to a composition of minerals such as stone, sand, gravel, and/or recycled products bound together by a product of crude oil and processed with heat. As used herein, “asphalt materials” refers to aggregate asphalt product (including stone, sand, gravel, additives, and/or recycled products. As used herein, unless context indicates otherwise, “flow rate” refers to mass flow rate. As used herein, “hot gas” refers to any gas hotter than ambient temperature, although in most examples in the present disclosure, the hot gas is at least several hundred degrees Fahrenheit or more.
Referring to
The system 100 further includes duct 106, valves 108 and 109, an exhaust bypass vent 110, and a dryer drum 112 having an inlet (not shown). The duct 106 connects the exhaust port of the generator 102 to the inlet of the dryer drum 112. In some embodiments, the exhaust bypass vent 110 is in fluid communication with the atmosphere. The valve 108 is disposed where the duct 106 meets the exhaust bypass vent 110 (i.e., at a junction between the duct 106 and the exhaust bypass vent 110). In some embodiments, the valve 108 is a gate valve. In some embodiments, the valve 109 is disposed where the duct 106 meets the dryer drum 112 (i.e., at a junction between the duct 106 and the dryer drum 112). In other embodiments, the valve 109 is disposed along the duct 106. In some embodiments, the valve 109 is a gate valve.
In some embodiments, the hot gas 4000 flows out of the gas turbine generator 102 through the outlet and flows inside the duct 106 (i.e., the duct 106 conveys a first flow Q1 of hot gas 4000 from the exhaust port). In some embodiments, when the valve 108 is at least partially open, at least some of the hot gas 4000 flows through the valve 108 and through the exhaust bypass vent 110 to atmosphere (i.e., the exhaust bypass vent 110 conveys a second flow Q2 of hot gas 4000 diverging from the first flow Q1 of hot gas 4000). In some embodiments, the valve 108 controls the flow of hot gas 4000 from the generator 102 to the atmosphere (i.e., the valve 108 is configured to adjust a flow rate of the second flow Q2 of hot gas 4000). In some embodiments, at least some of the hot gas 4000 from the generator 102 flows through the inlet of the dryer drum 112 (i.e., a third flow Q3 of hot gas 4000 diverges from the first flow Q1 of hot gas 4000 and enters the dryer drum 112 through the inlet). In some embodiments, after the second flow Q2 of hot gas 4000 passes through the exhaust bypass vent 110, the second flow of Q2 of hot gas 4000 further passes through an emissions control system before being vented to the atmosphere. The valve 109 also controls how much hot gas 4000 flows from the generator 102 through the inlet of the dryer drum 112 (i.e., the valve 109 is configured to adjust a flow rate of the third flow Q3 of hot gas 4000).
Aggregate asphalt material 5000 inside the dryer drum 112 is heated by the hot gas 4000 to produce the hot mix asphalt 6000. If the temperature is too low, the aggregate asphalt material 5000 inside the dryer drum 112 does not dry fast enough to produce hot mix asphalt 6000. At a nominal temperature, the aggregate asphalt material 5000 inside the dryer drum 112 dries sufficiently quickly and attains a sufficient temperature (e.g., 280° F. to 330° F.) to produce hot mix asphalt 6000. However, if the temperature is too high, the aggregate asphalt material 5000 inside the dryer drum breaks down, produces hydrocarbon fumes, and/or smokes. For successful production of hot mix asphalt 6000 from the aggregate asphalt material 5000, regulation of the temperature inside the dryer drum 112 is important. The temperature inside the dryer drum 112 is regulated at least in part by the valve 108. Control of the position of valve 108 is important for successfully processing the aggregate asphalt material 5000 into hot mix asphalt 6000. In some embodiments, the temperature inside the dryer drum 112 is also regulated at least in part by the valve 109.
In some embodiments, when the valve 108 is completely open, the flow of hot gas 4000 from the generator 102 to the atmosphere is maximized (i.e., the flow rate of the second flow Q2 of hot gas 4000 is maximized) and the flow of hot gas 4000 from the generator 102 to the dryer drum 112 is minimized (i.e., the flow rate of the third flow Q3 of hot gas 4000 is minimized). Thus, the interior of the dryer drum 112 tends to attain a relatively low temperature. In some embodiments, when the valve 108 is completely closed, there is no flow of hot gas 4000 from the generator 102 to the atmosphere (i.e., the flow rate of the second flow Q2 of hot gas 4000 is zero) and the flow of the hot gas 4000 from the generator 102 to the dryer drum 112 is maximized (i.e., the flow rate of the third flow Q3 of hot gas 4000 is maximized). Thus, the interior of the dryer drum 112 tends to attain a relatively high temperature, which is moderated by evaporating moisture from the aggregate, RAP, and RAS. In some embodiments, when the valve 108 is partially closed, the flow of hot gas 4000 to the generator 102 is moderate (i.e., the flow of the second flow Q2 of hot gas 4000 is moderate) and the flow of hot gas 4000 from the generator 102 to the dryer drum 112 is moderate (i.e., the flow rate of the third flow Q3 of the hot gas 4000 is moderate). Thus, the interior of the dryer drum 112 tends to attain a moderate temperature. In some embodiments, a flow rate of the first flow Q1 of hot gas 4000 is equal to the flow rate of the second flow Q2 of hot gas 4000 plus the flow rate of the third flow Q3 of hot gas 4000. In some embodiments, the valve 108 decreases a flow rate of the third flow Q3 of hot gas 4000 by increasing the flow rate of the second flow Q2 of hot gas 4000. In some embodiments, valve 108 is increases a flow rate of the third flow Q3 of hot gas 4000 by decreasing the flow rate of the second flow Q2 of hot gas 4000.
In some embodiments, the position of the valve 108 is controlled manually (e.g., by human input into a control panel managing a mechanical actuator or by a technician turning the valve 108 with a wrench) or automatically (e.g., by computer control). In some embodiments, a sensor (not shown) monitors temperature at the discharge of the dryer drum. In some embodiments, a processor (not shown) adjusts the position of the valve 108 by sending an electronic signal to the valve 108 based on the temperature detected by the discharge temperature sensor. In some embodiments, in response to detecting that the temperature is greater than a threshold, the processor opens the valve 108 by an amount. In some embodiments, the amount that the valve 108 is opened corresponds to an amount that the processor predicts will return the temperature to nominal. In some embodiments, in response to detecting that the temperature is less than a threshold, the processor closes the valve 108 by an amount. In some embodiments, the amount that the valve 108 is closed corresponds to an amount that the processor predicts will return the temperature to nominal.
Although in the embodiments described herein the exhaust (i.e., hot gas 4000) from the generator 102 is used to heat the asphalt material 5000 in the interior of the dryer drum 112, it is contemplated that in some embodiments, one or more other means of heating the aggregate asphalt material 5000 in the interior of the dryer drum 112 are additionally used. It is further contemplated that in some embodiments, the exhaust (i.e., hot gas 4000) is used for other purposes in addition to heating the aggregate asphalt material 5000 in the interior of the dryer drum 112.
Referring to
Referring to
In some embodiments, the inlet (not shown) is disposed at the first axial end 1122. In some embodiments the dryer drum 112 further comprises an opening (not shown) at the second axial end 1124 for loading the asphalt material 5000 and recycled materials into the dryer drum.
In some embodiments, a drive system (not shown) is configured to axially rotate the dryer drum. In some embodiments, the generator 102 supplies electrical energy to the drive system (i.e., the drive system is powered by the generator 102). In some embodiments, the dryer drum 112 produces the hot mix asphalt 6000 through the rotation of dryer drum 112 with the aggregate asphalt material 5000 inside the dryer drum 112 and the third flow Q3 flowing through the dryer drum 112. The rotation of the dryer drum mixes the aggregate asphalt material 5000 so that the aggregate asphalt material 5000 is more uniformly exposed to the flow of hot gas 4000 inside the dryer drum 112 and therefore is heated and dried more uniformly. The tilt of the dryer drum 112 helps draw aggregate asphalt material 5000 closer to the first axial end 1122, where the temperature is the greatest.
Referring to
Referring now to
In some embodiments of the method 400, the hot gas is exhaust gas produced by the running of the generator. In some embodiments of the method, the producing of the hot mix asphalt and the providing of the electrical energy to the power grid occur simultaneously.
The method and system of the present disclosure provide electrical energy 3000 and hot mix asphalt 6000. Instead of producing asphalt using a burner as in the related art, the method and system according to the present disclosure offer the advantage of producing substantial amounts of electricity in conjunction with asphalt production. The electricity produced by the system 100 can be sold to utility companies.
By drying the asphalt material 5000 with exhaust heat from the generator 102, the system 100 has the advantage of being capable of adjusting recycled content percentage of the aggregate asphalt material 5000 from 0-100% without limitation. The system 100 of the present disclosure also has the capacity to handle higher levels of recycled contents in the aggregate asphalt material 5000 as compared to the related art. For example, the system 100 of the present disclosure can use recycled asphalt products and recycled shingles at amounts of up to 100% of the aggregate asphalt material 5000 without the risk of fires and product damage caused by the direct flame burners of the conventional art.
The method and system according to the present disclosure also have the advantage of reduced emissions as compared to the conventional art. The method of producing the hot mix asphalt according to the present disclosure is more efficient than the conventional art because providing the heat for drying the aggregate asphalt material 5000 does not cause any emissions beyond those required for the generator 102 to generate useful electricity. The heat from running generator 102 (which would otherwise be wasted) is used to heat the aggregate asphalt material 5000 to produce the hot mix asphalt 6000.
Although the invention has been described and illustrated with respect to exemplary embodiments thereof, it should be understood by those skilled in the art that the foregoing and various other changes, omissions and additions may be made therein and thereto, without parting from the spirit and scope of the present invention.
