Batch asphalt mix plant

Abstract

The present disclosure relates to a plant for manufacturing heated asphalt mix. In particular, the disclosure relates to a batch asphalt mix plant for using a microwave heating vessel located in close proximity to a storage silo to heat asphalt mix at the point of storage using a batch production method.

Claims

1. A mobile batch asphalt mix plant, comprising: a trailer, an electric generator, a microwave energy system powered by the electric generator, a hopper configured to hold a quantity of unheated asphalt mix, one or more heating vessels, one or more wave guides configured to direct microwave energy from the microwave energy system into the one or more heating vessels for heating the asphalt mix, a conveyor configured to move unheated asphalt mix from the hopper to the one or more heating vessels for heating, one or more agitation mechanisms configured to blend at least the asphalt mix within the one or more heating vessels, and an elevated silo configured to receive heated asphalt mix from the one or more heating vessels as finished asphalt mix, the silo for storing the finished asphalt mix heated in the heating vessel with the microwave energy from the microwave energy system, and the silo positioned below at least one of the one or more heating vessels.

2. The mobile batch asphalt mix plant of claim 1, wherein the asphalt mix comprises aggregate, asphalt emulsion, asphalt binder or binder component(s), softening or rejuvenating oil, aggregate blend, asphalt blend, treated aggregate, RAP, RAS, 100% RAP, or combinations thereof.

3. The mobile batch asphalt mix plant of claim 1, wherein the microwave energy system comprises a single microwave transmitter or a plurality of microwave transmitters.

4. The mobile batch asphalt mix plant of claim 1, wherein at least one of asphalt binder or asphalt emulsion is added to the asphalt mix.

5. The mobile batch asphalt mix plant of claim 4, wherein the at least one of asphalt binder or asphalt emulsion is added to the asphalt mix within the one or more heating vessels.

6. The mobile batch asphalt mix plant of claim 5, wherein the one or more agitation mechanisms are configured to blend the asphalt mix, including the added asphalt binder or asphalt emulsion, during heating.

7. The mobile batch asphalt mix plant of claim 6, wherein the one or more agitation mechanisms comprise a plurality of paddles that move the asphalt mix, including the added asphalt binder or asphalt emulsion, from one side of the heating vessel to another side of the heating vessel during heating.

8. The mobile batch asphalt mix plant of claim 1, further comprising a combiner, wherein the combiner is a pug mill configured to blend the heated finished asphalt mix before being moved to the silo for storage.

9. The mobile batch asphalt mix plant of claim 1, wherein the one or more wave guides are positioned along a side of and/or under the conveyor.

10. The mobile batch asphalt mix plant of claim 1, wherein the one or more wave guides are attached to the conveyor.

11. The mobile batch asphalt mix plant of claim 1, wherein the one or more heating vessels comprises at least a drum dryer heater.

12. The mobile batch asphalt mix plant of claim 1, wherein the one or more agitation mechanisms are configured to blend at least the asphalt mix within the one or more heating vessels during heating.

13. The mobile batch asphalt mix plant of claim 1, wherein the elevated silo is configured to dispense finished asphalt mix into one or more trucks that can drive under the elevated silo.

14. A stationary batch asphalt mix plant, comprising: a source of electricity, a microwave energy system powered by the source of electricity, a hopper configured to hold a quantity of unheated asphalt mix, one or more heating vessels, one or more wave guides configured to direct microwave energy from the microwave energy system into the one or more heating vessels for heating the asphalt mix, a conveyor configured to move unheated asphalt mix from the hopper to the one or more heating vessels for heating, one or more agitation mechanisms configured to blend at least the asphalt mix within the one or more heating vessels, and an elevated silo configured to receive heated asphalt mix from the one or more heating vessels as finished asphalt mix, the silo for storing the finished asphalt mix heated in the heating vessel with the microwave energy from the microwave energy system, and the silo positioned below at least one of the one or more heating vessels.

15. The stationary batch asphalt mix plant of claim 14, wherein the asphalt mix comprises aggregate, asphalt emulsion, asphalt binder or binder component(s), softening or rejuvenating oil, aggregate blend, asphalt blend, treated aggregate, RAP, RAS, 100% RAP, or combinations thereof.

16. The stationary batch asphalt mix plant of claim 14, wherein the microwave energy system comprises a single microwave transmitter or a plurality of microwave transmitters.

17. The stationary batch asphalt mix plant of claim 14, further comprising a combiner, wherein the combiner is a pug mill to blend the heated finished asphalt mix before being moved to the silo for storage.

18. The stationary batch asphalt mix plant of claim 14, wherein at least one of asphalt binder or asphalt emulsion is added to the asphalt mix.

19. The stationary batch asphalt mix plant of claim 18, wherein the at least one of asphalt binder or asphalt emulsion is added to the asphalt mix within the one or more heating vessels.

20. The stationary batch asphalt mix plant of claim 19, wherein the one or more heating vessels contain agitation mechanisms configured to blend the asphalt mix and the added asphalt binder or asphalt emulsion during heating.

21. The stationary batch asphalt mix plant of claim 20, wherein the one or more agitation mechanisms comprise a plurality of paddles that move the asphalt mix and the added asphalt binder or asphalt emulsion from one side of the heating vessel to another side of the heating vessel during heating.

22. The stationary batch asphalt mix plant of claim 14, wherein the one or more agitation mechanisms are configured to blend at least the asphalt mix within the one or more heating vessels during heating.

Description

DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a perspective view illustrating an embodiment of a mobile asphalt mix plant with a Low Energy Heating System (“LEHS”).

(2) FIG. 2 illustrates top, front and side views of the mobile asphalt mix plant shown in FIG. 1.

(3) FIG. 3 illustrates an alternative embodiment of a batcher for use with the mobile asphalt mix plant of FIG. 1.

(4) FIG. 4 illustrates another alternative embodiment of a batcher for use with the mobile asphalt mix plant of FIG. 1.

(5) FIG. 5 illustrates an embodiment of a batcher for use with an asphalt mix plant.

(6) FIG. 6 is a side view illustrating an embodiment of a stationary asphalt mix plant with a LEHS.

(7) FIG. 7 is side, front and top views of a mobile asphalt mix plant with a LEHS.

(8) FIG. 8 is close up side view of the batch heating vessel and pug mill of FIG. 7.

(9) FIG. 9 illustrates an alternative embodiment of a modular asphalt mix plant with a LEHS.

(10) FIG. 10 illustrates various means of loading asphalt mix into the batch heating vessel.

(11) FIGS. 11-15 show additional views from different perspectives or the various levels of the modular asphalt mix plant with a LEHS of FIG. 9.

(12) FIG. 16 is section and cross section views of a microwave heating vessel.

(13) FIG. 17 is a side cross sectional view of a combiner.

DETAILED DESCRIPTION OF THE INVENTION

(14) FIGS. 1-17 illustrate embodiments of an asphalt mix plant having a vessel comprising a microwave heated batcher, embodiments of an asphalt mix plant having a vessel consisting essentially of a microwave heated batcher, embodiments of an asphalt mix plant having a vessel consisting of a microwave heated batcher. In particular, FIG. 1 shows the general configuration of an embodiment of the present description. This embodiment comprises a mobile version of an asphalt mix plant 10. The asphalt mix plant 10 includes a flatbed trailer 12 upon which components of the asphalt mix plant are mounted, and which can be towed from site to site. In other embodiments, an asphalt mix plant may be a stationary mini asphalt mix plant that can be mobile, or stationary.

(15) An electrical generator 14 is located on the trailer 12 to provide electricity to power the plant, or a connection for house power is provided (which is especially useful with the stationary plant configuration). The generator 14 can run on a variety of fuels such as diesel, fuel oil, gasoline, natural gas, and the like. Also, provided is a microwave energy system 16, and in particular a Low Energy Heating System (“LEHS”), wherein a LEHS power unit powers a plurality of microwave transmitters. The LEHS power unit typically includes a plurality of microwave transmitter units (not shown) with a splitter/wave guides that direct microwave energy from each transmitter into one or more rotary head heating chambers, stationary corporate wave guides can also be used, using either 2.4 GHz or 915 MHz. The microwave process is referred to in this disclosure as LEHS or as a mobile low energy heating system (“MLEHS”). Using a single or multiple microwaves transmitters in a series gives the ability to cycle the power and intensity to achieve the best heating results over a controlled surface. The microwave energy in FIG. 1 is channeled through a wave guide 18 that runs along the side of, or under, a drag line (slat conveyor) 20 (explained in detail below).

(16) A hopper is provided where unheated aggregate or a mixture of unheated aggregate and RAP (or alternatively RAS) is loaded. This aggregate material may be loaded from stockpiles using a front end loader or in some instances may be brought to a mixing site in super sacks 22. In some embodiments, the aggregate is combined or treated with an emulsified asphalt binder when it is used in the disclosed batched asphalt mix plant.

(17) The aggregate material is carried along the top of drag line (slat conveyor) 20, where it then falls into a drop chute 24, and then into the LEHS batcher 26. The batcher 26 receives the microwave energy from the wave guide 18. The asphalt mix is heated in the batcher 26 and the entire batch is then delivered to a silo 28. The finished asphalt mix can be stored in the silo until it is loaded into a truck. In another embodiment, the heating vessel is designed without any agitation mechanism and instead uses additional wave guide splits (not shown) that can be mounted either on the top of the silo or on the ground where heating can occur, and then conveyance of the heated material to the silo for storage. Ramps 29 are provided (or gravel can be used) to allow the truck to move under the silo for material loading. The silo 28 is on a tilt-able mount and can be moved to a flat position on the trailer for transportation. FIG. 2 shows additional views of the asphalt mix plant shown in FIG. 1.

(18) FIG. 3 shows various views of a batcher 30 that can substituted for the drop chute shown in FIGS. 1 and 2. The batcher 30 is affixed to the terminal end of slat conveyor 32. In particular, asphalt mix is dropped from the conveyor 32 into the batcher, which when full is emptied by opening the hinged door 34 at the bottom of the batcher 30. The door 34 is moved by a hydraulic cylinder(s) 36 that moves the door between an opened and closed position. Microwave energy can be directed to the batcher in the manner shown in reference to FIGS. 1 and 2. A wave guide (not shown in FIG. 3) can be attached to the slat conveyor 32, and the energy released into the interior of the batcher 30.

(19) FIG. 4 shows various views of another batcher 40 that can be used with the mobile asphalt mix plant illustrated in FIGS. 1 and 2. The batcher would receive asphalt mix from a dragline (slat conveyor) (not shown in FIG. 4), but does not necessarily have to be physically connected to the conveyor as illustrated in FIG. 3. Two hydraulic cylinders 42a and 42b on opposite sides of the batcher 40 open and close a swinging door 44 at the bottom of the batcher. Microwave energy can be directed to the interior of batcher as described above.

(20) FIG. 5 shows another embodiment of a batcher 50 that comprises an LEHS cavity 52 between the bulk drop container 54 and the silo 56. The bulk drop container 54 includes bulk drop doors 55a and 55b which when open allow asphalt mix in the container 52 to fall into the LEHS cavity 54. Further, stainless steel doors 57a and 57b at the top of the silo can be opened and closed to receive finished asphalt mix either in batches or continuously. The LEHS cavity is preferably constructed of stainless steel which is not magnetic and is not a good conductor of microwave energy making it suitable for use with microwaves; other similar materials can be used such as aluminum (for example).

(21) In order to more effectively heat the material a mixer 58 is provided, having a plurality of paddles 58a (preferably stainless steel) that move the material from one side of the cavity to the other and back again. In another embodiment, this mixing can occur outside the LEHS cavity, with a detached mixer (not shown). The mixer 58 is powered by motor 59 attached to the side of the LEHS cavity. Microwave energy enters the LEHS cavity through a wave guide 51. After the bituminous mixture is heated by the microwave energy, the mixture is dropped through doors 57a and 57b at the bottom of the LEHS cavity into the silo for storage and eventual distribution.

(22) In one embodiment, the asphalt mix plant is mobile; however, the disclosed microwave batcher/cavity can be adapted to a stationary asphalt mix plant as well. The asphalt mix plant can be used with super sacks of aggregate, treated aggregate, with some percentage RAP (including up to 100% RAP), RAS or combinations thereof. Depending on the anticipated amount of finished asphalt mix needed, the time of year, and geographical location the aggregate, treated aggregate, RAS and/or RAP can be stockpiled outside or inside a building. The microwave batcher cavity or vessel is adapted for heating batch sizes in the range of 1 to 4 tons of bituminous mixture, which is typically heated to a temperature in a range of about 280° F. to 325° F. The target heating temperature will vary depending on the type of bituminous mixture or asphalt used, the time of year, and hauling distance and in some instances could be outside the typical target temperature range stated above. The silo can hold in the range of 50-75 tons of finished asphalt mix.

(23) As shown above the disclosed asphalt mix plant may include a microwave heating vessel that is attached to the end of the conveyor, that sits between the slat conveyor and silo but is attached to the silo, or alternatively the heating vessel can be located in the silo itself. In particular, the heating vessels illustrated in FIGS. 1, 2, and 5 can be recessed into the actual silo rather than located at a site above the silo.

(24) FIG. 6 shows a stationary version of the asphalt mix plant 60, which is substantially similar to the mobile version but can be fixed to a particular location. The stationary version includes a hopper 61 that can accommodate aggregate, treated aggregate, RAP, RAS or combinations thereof mixed on site, or similar materials loaded from super sacks. A power generator 62 and LEHS power unit 63 are located at ground level. A drag line (slat conveyor) 64 moves aggregate, treated aggregate, RAP, RAS or combinations thereof up to the batcher, and a wave guide 65 runs along the underside of the drag line 64 to channel the microwave energy upward as well. As with the mobile plant, the stationary plant can use a batch heating vessel 66 located at the end of the drag line (slat conveyor), or a vessel that is attached to or enclosed within the silo 67.

(25) FIG. 7 illustrates an embodiment of a mobile version of the asphalt mix plant 70, which includes a mobile power unit housing a generator 71 and the LEHS microwave power plant 72, and an aggregate, treated aggregate, RAP, RAS or combinations thereof loader 73. The aggregate, treated aggregate, RAP, RAS or combinations thereof is moved up a drag line (slat conveyor) 74, with the wave guides 75 mounted under the drag line (slat conveyor). A batch heating vessel 76 receives aggregate, treated aggregate, RAP, RAS or combinations thereof from the drag line (slat conveyor) 74 and microwave energy is directed into the LEHS cavity through various distribution conduits arranged in a ring around the vessel. The finished asphalt mix after being heated moves from the vessel into a pug mill 77 that uses paddles to mix the finished asphalt mix, which then moves into a silo 78. The entire plant is mounted on one or more trailers 79a and 79b, and can be moved as needed.

(26) FIG. 8 is a close up view of the batch heating vessel 76 and pug mill 77 of FIG. 7. The microwave energy is channeled into a ring 80 that allows the energy to be evenly distributed into various input feed take off chutes 80a, 80b, 80c and 80d, so that the energy enters the vessel from a number of distributed areas. Doors 82 at the top of the vessel/cavity can be opened and closed to receive and heat a batch of aggregate, treated aggregate, RAP, RAS or combinations thereof. Doors 84 at the bottom of the vessel are similarly opened and closed to move the heated aggregate, treated aggregate, RAP, RAS or combinations thereof, and optional asphalt binder (if needed or used) to the pug mill 77 for mixing. A motor 85 drives paddles 86 that mixes the heated aggregate, treated aggregate, RAP, RAS or combinations thereof, and optional asphalt binder (if needed or used) to more evenly distribute the heat, and then the finished asphalt mix in the pug mill drops through doors 88 into the silo 78 below. All of the areas that receive or process heated aggregate, treated aggregate, RAP, RAS or combinations thereof, and optional asphalt binder (if needed or used) are insulated to prevent heat loss, or are provided with a jacket that is heated with circulating oil.

(27) FIG. 9 shows an alternative embodiment of an asphalt mix plant with a LEHS comprising a modular asphalt mix plant. The disclosed asphalt mix plant 90 includes two T-shaped wings 91 and 92. Generally, one wing 91 houses various facility components primarily related to microwave operation 91, and the other wing 92 comprises a series of silos for storage of the finished asphalt mix.

(28) In particular, this figure illustrates 3 modular silos (labeled 94A, 94B, 94C and shown transparently in FIG. 9); however, more or less silos can be included. The silos allow for dispensing finished asphalt mix into trucks that can drive under the silos. Load cells are incorporated under the silos to weigh finished asphalt mix as it is dispensed.

(29) Finished asphalt mix is moved to the silos by a combiner 96, which uses a series of paddles (not shown) to move and mix the finished asphalt mix from the microwave rotary heating vessel 98 to the silos 94A, 94B and 94C. Drop chutes (not shown) located on the underside of the combiner allow the finished asphalt mix to drop from the combiner into the chosen silo. The drop chutes can be mechanically operated to allow for selection between the silos, such that the silos can be filled on demand. For example, diverters can be used to channel the flow of the finished asphalt mix to the appropriate drop chute and silo. The silos, as well as the combiner are wrapped in insulated jackets, and an oil boiler (or similar system) can be used to circulate hot oil thereto to ensure that the finished asphalt mix is kept at a stable elevated temperature after leaving the microwave vessel in a target temperature range of about 280° F. to 325° F.

(30) FIG. 10 is a side view of the modular asphalt mix plant with a LEHS shown in FIG. 9. The facilities section of the plant is comprised of roughly 4 levels. The bottom level 101 can store facility equipment such as a chiller unit that provides cooling for the microwave units described below, or for any other purpose. A generator can be housed on this level, to provide primary or back up electricity to the plant.

(31) The second level 102 can include space for offices, as well as facility equipment such as the HVAC unit for heating and cooling any of the various areas of the plant including the vessel area as well as the office space.

(32) FIG. 10 also illustrates various means of loading asphalt mix into the batch heating vessel 104. These include the use of a conveyor 103, either belt or paddle driven. Alternatively a bucket conveyor can be used as well. The top of the vessel includes loading doors 105 that can be opened and closed as needed to load asphalt mix, and to accommodate the heating step. As provided above, the asphalt mix may come from various sources such as aggregate, treated aggregate, RAP, RAS or combinations thereof.

(33) At the second highest level 106 LEHS power units are located. The power units are electrically power and included a magnetron for generating microwave energy. Wave guides channel the microwave energy waves to the heating vessel. The microwaves can be introduced into to the vessel directly or using rotary joints.

(34) FIGS. 11-15 show additional views from different perspectives or the various levels of the modular asphalt mix plant 100 with a LEHS shown in FIG. 9, and illustrate the matter disclosed above in additional detail.

(35) FIG. 16 shows section and cross section views of a microwave heating vessel 110, in which aggregate, treated aggregate RAP, RAS or combinations thereof is heated in batches by the LEHS microwave system. The aggregate, treated aggregate RAP, RAS or combinations thereof is loaded into the heating vessel from the top through doors 111 that can be opened for loading and closed for heating. Microwave energy enters the vessel from a variety of entry ports 112 to provide for distributing the energy throughout the heating vessel. The vessel is lined with a ceramic material, or some other similar material, that is not susceptible to heating when exposed to microwave energy, and is durable enough to handle asphalt mixt. After heating, exit gates 114 are opened to allow the heated finished asphalt mix to drop into the combiner or silo for storage of the heated finished asphalt mix. In FIG. 16, the four wave guides 112 are stacked on top of one another, however, they can be placed side-by-side, where there are four wave guides two on each side; however, the wave guides on arranged horizontally instead of vertically.

(36) FIG. 17 is a side cross sectional view of a combiner for the use in the disclosed asphalt mix plant. As described above, finished asphalt mix can move from the microwave heating vessel into the combiner 120 for distribution to the appropriate silo. Alternatively, the heating vessel can be omitted with the heating taking place in the combiner 120 by channeling the microwave energy through wave guides 125 connected at various locations along the length of the combiner.

(37) The finished asphalt mix is introduced into the combiner 120 through a hatch 121 that can be open and closed as needed. A set of paddles 122 move the finished asphalt mix along the length of the combiner under the power of an electric motor 123. Exit gates 124 are located along the bottom of the combiner over the silos (not shown), which can be selectively opened and closed to fill the silos. The combiner 120 is preferably insulated to avoid heat loss, and lined with a material that is not susceptible to microwave heat such as stainless steel. Heated oil can be circulated through the lining of the combiner to heat the combiner to a temperature consistent with that of the finished asphalt mix.

(38) The advantage of the present invention is that it greatly simplifies the components of an asphalt mix plant and in particular a mobile plant. By eliminating the need for a large costly heater the present invention greatly reduces the required infrastructure and cost associated with prior art plants. Further, the heating step is moved to the point of storage which also reduces the amount of infrastructure. For example, since heated asphalt mix is no longer moved on a conveyor, the conveyor experiences far less wear and tear which occurs when the belts move heated asphalt mix. The present invention allows for small cost effective mobile plants to be used in environments where it was not cost effective in the past. Still further, the present invention makes it possible for retail providers of cold mix asphalt to easily provide hot mix asphalt by reducing the cost of such a plant, and the space needed for a plant. The asphalt mix plant of the present invention can be used at a retail home center and the like to provide hot mix asphalt. Municipalities which lack the demand for a dedicated prior art asphalt mix plant, can now afford to have a plant or more easily set up a temporary mobile plant at any time instead of waiting until long periods of time until the demand justified the investment.

(39) These and other advantages will be apparent to those of ordinary skill in the art.

(40) While the various embodiments of the invention have been described, the invention is not so limited. Also, the method and apparatus of the present invention is not necessarily limited to any particular field, but can be applied to any field where an interface between a user and a computing device is applicable. There are two earlier filed and related U.S. patent applications, U.S. Ser. Nos. 13/887,828 and 13/887,859; the disclosures of which are hereby incorporated by reference.

(41) Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although methods and materials similar to or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods, and materials are described below. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety to the extent allowed by applicable law and regulations. In case of conflict, the present specification, including definitions, will control.

(42) The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and it is therefore desired that the present embodiment be considered in all respects as illustrative and not restrictive, reference being made to the appended claims rather than to the foregoing description to indicate the scope of the invention. Those of ordinary skill in the art that have the disclosure before them will be able to make modifications and variations therein without departing from the scope of the invention.