US2015345085A1PendingUtilityA1

Multiple-entry hot-mix asphalt manufacturing system and method

37
Individually held — no corporate assignee on recordPriority: May 29, 2014Filed: May 27, 2015Published: Dec 3, 2015
Est. expiryMay 29, 2034(~7.8 yrs left)· nominal 20-yr term from priority
Inventors:Robert Frank
E01C 19/1027E01C 19/1036E01C 2019/109
37
PatentIndex Score
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Cited by
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References
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Claims

Abstract

A hot-mix asphalt manufacturing system for recycled asphalt coated aggregate (RAP) has a rotary dryer and burner operable to heat the dryer to create a maximum gas temperature at a location between first and second ends of the dryer. A first inlet is upstream and a second inlet is downstream of the maximum temperature. A first coarse aggregate is introduced through the first inlet, fine RAP is introduced through the second inlet, and the aggregates are heated and mixed forming a mixture outputted at an outlet. For 100% RAP processes, the first and second aggregates can consist of RAP. For less than 100% RAP processes, virgin aggregate can be introduced through the first inlet, located adjacent the first end of the rotary dryer, and a third inlet can be located between the maximum temperature and the first inlet, with fine and coarse RAP introduced through the second and third inlets.

Claims

exact text as granted — not AI-modified
What is claimed is: 
     
         1 . A method of manufacturing asphalt using recycled asphalt coated aggregate (RAP), comprising:
 providing a rotary dryer having
 a first end and a second end, and a material stream flow toward the second end; 
 a burner operable to heat the rotary dryer and material therein, and to create a maximum gas temperature inside a volume of the rotary dryer at a location between the first and second ends, 
 a first inlet upstream of the location of the maximum temperature, 
 a second inlet downstream of the location of the maximum temperature, and 
 an outlet adjacent the second end of the rotary dryer; 
   selecting a first aggregate and a second aggregate, the first aggregate being at least primarily coarse aggregate and the second aggregate being at least primarily fine RAP;   operating the rotary dryer and during the operation
 introducing the first aggregate into the rotary dryer at the first inlet, 
 introducing the second aggregate into the rotary dryer at the second inlet, and 
 heating and mixing the first and second aggregates forming a mixture; and 
   outputting the mixture from the rotary dryer at the outlet.   
     
     
         2 . The method of  claim 1 , wherein the first aggregate is at least primarily coarse RAP. 
     
     
         3 . The method of  claim 1 , wherein the second aggregate consists essentially of fine RAP. 
     
     
         4 . The method of  claim 3 , wherein the first aggregate is at least primarily coarse RAP. 
     
     
         5 . The method of  claim 4 , wherein the first aggregate consists essentially of coarse RAP. 
     
     
         6 . The method of  claim 5 , wherein the second aggregate consists of fine RAP. 
     
     
         7 . The method of  claim 6 , wherein the first aggregate consists of coarse RAP. 
     
     
         8 . The method of  claim 1 , wherein:
 only coarse RAP is introduced into the rotary dryer at the first inlet; and   only fine RAP is introduced into the rotary dryer at the second inlet.   
     
     
         9 . The method of  claim 1 , further comprising:
 providing the first inlet adjacent the first end of the rotary dryer, and the first aggregate being at least primarily coarse virgin aggregate;   providing a third inlet between the first inlet and the location of the maximum temperature;   selecting a third aggregate, the third aggregate being at least primarily coarse RAP; and   during the operation, introducing the third aggregate into the rotary dryer at the third inlet.   
     
     
         10 . The method of  claim 9 , wherein the second aggregate consists essentially of fine RAP. 
     
     
         11 . The method of  claim 9 , wherein the third aggregate consists essentially of coarse RAP. 
     
     
         12 . The method of  claim 9 , wherein the first aggregate consists essentially of coarse virgin aggregate. 
     
     
         13 . The method of  claim 9  wherein the second aggregate consists of fine RAP. 
     
     
         14 . The method of  claim 9 , wherein the third aggregate consists of coarse RAP. 
     
     
         15 . The method of  claim 9 , wherein the first aggregate consists of coarse virgin aggregate. 
     
     
         16 . The method of  claim 9 , wherein
 only virgin aggregate is introduced into the rotary dryer at the first inlet; and   only RAP is introduced into the rotary dryer at the second and third inlets.   
     
     
         17 . The method of  claim 16 , wherein
 only fine RAP is introduced into the rotary dryer at the second inlet; and   only coarse RAP is introduced into the rotary dryer at the third inlet.   
     
     
         18 . The method of  claim 9 , wherein coarse RAP aggregate comprises approximately 55% to 75% of a total RAP content in the mixture, and fine RAP aggregate comprises approximately 25% to 45% of the total RAP content in the mixture. 
     
     
         19 . The method of  claim 1 , wherein the mixture comprises at least 40% RAP. 
     
     
         20 . The method of  claim 1 , wherein the mixture comprises at least 75% RAP. 
     
     
         21 . The method of  claim 1 , wherein the mixture comprises at least 95% RAP. 
     
     
         22 . The method of  claim 1 , wherein the rotary dryer comprises a counter flow dryer. 
     
     
         23 . The method of  claim 1 , wherein the rotary dryer is in a continuous mix plant. 
     
     
         24 . The method of  claim 1 , further comprising:
 providing a batch asphalt plant having a mixer separate from the rotary dryer;   introducing the mixture output from the rotary dryer into the mixer;   introducing a supplemental ingredient into the mixer; and   operating the mixer forming a second mixture.   
     
     
         25 . The method of  claim 1 , wherein the selecting comprises classifying fine aggregate as aggregate that fits through a #4 sieve and classifying coarse aggregate as aggregate that does not fit through a #4 sieve. 
     
     
         26 . The method of  claim 1 , wherein the selecting comprises classifying fine aggregate as sands and classifying coarse aggregate as stones. 
     
     
         27 . The method of  claim 1 , further comprising a pollution control device having a fiber bed filter, the pollution device treating emissions from the rotary dryer. 
     
     
         28 . The method of  claim 1 , wherein the maximum temperature of the rotary dryer is less than 1500 F. 
     
     
         29 . The method of  claim 9 , wherein a temperature profile of the rotary dryer defines
 a drying zone adjacent the first end and having a material temperature in a range of 50-350 F;   a combustion zone between the drying zone and the second end and having an air temperature in a range of 700-1500 F;   a mixing zone between the combustion zone and the second end and having a material temperature in a range of 250-350 F; and   wherein the second and third inlets are located in the combustion zone.   
     
     
         30 . The method of  claim 29  wherein a supplemental ingredient is introduced into the rotary dryer in the mixing zone. 
     
     
         31 . The method of  claim 30  wherein the supplemental ingredient comprises asphalt cement and/or recycling agents. 
     
     
         32 . The method of  claim 1 , wherein the rotary dryer has a dam at a lower end of the combustion zone that maintains a depth of aggregate inside the rotary dryer while it rotates. 
     
     
         33 . The method of  claim 1 , further comprising:
 placing insulation on the inside of the rotary dryer; and   attaching insulator flights to the rotary dryer radially inwardly of the insulation, the insulator flights lining at least a portion of the inside of the rotary dryer.   
     
     
         34 . The method of  claim 33 , wherein the insulator flights comprise overlapping rectangular metal segments. 
     
     
         35 . The method of  claim 33 , wherein the insulation comprises ceramic insulation. 
     
     
         36 . The method of  claim 33 , further comprising:
 attaching lifting flights to the insulator flights, the lifting flights being operable to agitate aggregate as the rotary dryer rotates.   
     
     
         37 . The method of  claim 33 , wherein the insulator flights are located substantially throughout the rotary dryer between the first and second ends. 
     
     
         38 . The method of  claim 33 , wherein the rotary dryer has no external insulation. 
     
     
         39 . Use of the method for manufacturing asphalt of  claim 1  in a portable unitized mix plant. 
     
     
         40 . The method of  claim 1 , wherein the burner has a tubular extension with an end; and the providing a second inlet comprises shortening the tubular extension so that the second inlet is between the end of the tubular extension and the location of the maximum temperature. 
     
     
         41 . The method of  claim 9 , wherein the providing a third inlet comprises affixing a collar to the rotary dryer.

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