Counter-flow drum mixer asphalt plant with two stage mixing zone
IPC분류정보
국가/구분
United States(US) Patent
등록
국제특허분류(IPC7판)
B28C-005/46
B28C-005/00
출원번호
US-0386070
(2003-03-11)
등록번호
US-7357562
(2008-04-15)
발명자
/ 주소
Hawkins,Michael R.
출원인 / 주소
Hawkins,Michael R.
대리인 / 주소
Bowman,Joseph B
인용정보
피인용 횟수 :
5인용 특허 :
38
초록▼
A counter-flow drum mixer asphalt plant equipped with a secondary feeder for introducing RAP to direct radiant heat of the combustion zone. Heated virgin aggregate and RAP in the combustion zone are delivered through a transition piece to a first stage of the mixing zone where liquid asphalt is comb
A counter-flow drum mixer asphalt plant equipped with a secondary feeder for introducing RAP to direct radiant heat of the combustion zone. Heated virgin aggregate and RAP in the combustion zone are delivered through a transition piece to a first stage of the mixing zone where liquid asphalt is combined with the materials and secondary combustion air flows through the first stage to evacuate blue smoke and steam back to the combustion zone. The second stage of the mixing zone is substantially isolated from secondary combustion air flow where dust and mineral fines are introduced and mixed to complete the asphalt product discharged from the mixing zone. Alternative constructions of the mixing zone are disclosed to provide the first and second stages having such characteristics, as well as options for both the passive and active control of the secondary combustion air. An optional secondary burner in the exhaust housing elevates the temperature of the exhaust gas above its dew point temperature before delivery to the baghouse.
대표청구항▼
Having thus described my invention, I claim: 1. A counter-flow drum mixer asphalt plant for producing asphaltic product from aggregate and liquid asphalt, said asphalt plant comprising: a rotatable cylinder having first and second ends with an internal passageway communicating therebetween and seri
Having thus described my invention, I claim: 1. A counter-flow drum mixer asphalt plant for producing asphaltic product from aggregate and liquid asphalt, said asphalt plant comprising: a rotatable cylinder having first and second ends with an internal passageway communicating therebetween and serially providing zones therein from said first end to said second end defined progressively as a drying zone, a combustion zone and first and second stage mixing zones; a support framework carrying said cylinder in a substantially horizontal orientation; a drive motor mounted on said framework and engaged with said cylinder to rotate said cylinder about the central longitudinal axis thereof; a primary aggregate feeder with a material discharge extending within said first end of said cylinder to deliver aggregate material to said drying zone of said cylinder whereby rotation of said cylinder transports said aggregate material progressively through said drying, combustion and first and second stage mixing zones to said second end of said cylinder; a combustion assembly projected into the second end of said cylinder and extending through said first and second stage mixing zones to said combustion zone to generate a hot gas stream in said combustion zone to flow through said combustion and drying zones toward said first end of said cylinder in a countercurrent direction to the flow of aggregate material within said cylinder in order to heat and dry the aggregate material within said combustion and drying zones, said combustion assembly including a burner head positioned at said combustion zone, a fuel supply connected to said burner head, and a primary combustion air supply connected to said burner head to establish a combustion flame within said combustion zone of said cylinder; a liquid asphalt feeder disposed within said first stage mixing zone for delivering liquid asphalt to the hot aggregate carried from the combustion zone into said first stage mixing zone to form an asphaltic composition; a dust feeder disposed within said second stage mixing zone for delivering fine additives to said asphaltic composition carried from said first mixing zone to form a finished asphaltic product; a stationary discharge housing sealingly connected to said second end of said cylinder to permit rotation thereof and having a discharge port for discharging said finished asphaltic product from said cylinder; and a secondary combustion air supply connected to said discharge housing to direct a flow of secondary combustion air to said first stage mixing zone in order to evacuate and carry blue smoke and steam vapors from said first stage mixing zone into said combustion zone and to substantially isolate said second stage mixing zone from the flow of secondary combustion air in order to minimize entrainment of fine additives from said second stage mixing zone. 2. The counter-flow drum mixer asphalt plant as in claim 1, said secondary combustion air supply including an opening in said discharge housing to admit ambient air and a conduit member associated with said opening to direct air flow to said first stage mixing zone and to substantially shield said second stage mixing zone from air flow. 3. The counter-flow drum mixer asphalt plant as in claim 2, said conduit member comprising a teepee shield interposed between said opening in said discharge housing and said dust feeder. 4. The counter-flow drum mixer asphalt plant as in claim 2, said conduit member comprising a cylindrical tube connected to said opening in said discharge housing and extended through said second stage mixing zone to deliver secondary combustion air to said first stage mixing zone. 5. The counter-flow drum mixer asphalt plant as in claim 1, said dust feeder comprising a tubular auger having a plurality of discharge openings along the length thereof to deliver fine additives and a pair of flexible shields suspended from said tubular auger along opposite sides of said discharge openings to direct fine additives downwardly to said asphaltic composition within said second stage mixing zone. 6. A counter-flow drum mixer asphalt plant for producing asphaltic product from aggregate, RAP, and liquid asphalt, said asphalt plant comprising: a rotatable cylinder having first and second ends with an internal passageway communicating therebetween and serially providing zones therein from said first end to said second end defined progressively as a drying zone, a combustion zone and first and second stage mixing zones; a support framework carrying said cylinder in a substantially horizontal orientation; a drive motor mounted on said framework and engaged with said cylinder to rotate said cylinder about the central longitudinal axis thereof; a primary aggregate feeder with a material discharge extending within said first end of said cylinder to deliver aggregate material to said drying zone of said cylinder whereby rotation of said cylinder transports said aggregate material progressively through said drying, combustion and first and second stage mixing zones to said second end of said cylinder; a combustion assembly projected into the second end of said cylinder and extending through said first and second stage mixing zones to said combustion zone to generate a hot gas stream in said combustion zone to flow through said combustion and drying zones toward said first end of said cylinder in a countercurrent direction to the flow of aggregate material within said cylinder in order to heat and dry the aggregate material within said combustion and drying zones, said combustion assembly including a burner head positioned at said combustion zone, a fuel supply connected to said burner head, and a primary combustion air supply connected to said burner head to establish a combustion flame within said combustion zone of said cylinder; a recycle feeder to introduce RAP into said combustion zone of said cylinder; a liquid asphalt feeder disposed within said first stage mixing zone for delivering liquid asphalt to the hot aggregate and RAP material carried from the combustion zone into said first stage mixing zone to form an asphaltic composition; a dust feeder disposed within said second stage mixing zone for delivering fine additives to said asphaltic composition carried from said first mixing zone to form a finished asphaltic product; a stationary discharge housing sealingly connected to said second end of said cylinder to permit rotation thereof and having a discharge port for discharging said finished asphaltic product from said cylinder; and a secondary combustion air supply connected to said discharge housing to direct a flow of secondary combustion air to said first stage mixing zone in order to evacuate and carry blue smoke and steam vapors from said first stage mixing zone into said combustion zone and to substantially isolate said second stage mixing zone from the flow of secondary combustion air in order to minimize entrainment of fine additives from said second stage mixing zone. 7. The counter-flow drum mixer asphalt plant as in claim 6, said recycle feeder located from said first stage mixing zone a distance within the range of 2 to 8 feet in order to limit the residence time of said RAP material within said combustion zone before delivery to said first stage mixing zone. 8. The counter-flow drum mixer asphalt plant as in claim 6, said secondary combustion air supply including an opening in said discharge housing to admit ambient air and a conduit member associated with said opening to direct air flow to said first stage mixing zone and to substantially shield said second stage mixing zone from air flow. 9. The counter-flow drum mixer asphalt plant as in claim 8, said conduit member comprising a teepee shield interposed between said opening in said discharge housing and said dust feeder. 10. The counter-flow drum mixer asphalt plant as in claim 8, said conduit member comprising a cylindrical tube connected to said opening in said discharge housing and extended through said second stage mixing zone to deliver secondary combustion air to said first stage mixing zone. 11. The counter-flow drum mixer asphalt plant as in claim 6, said secondary combustion air supply including a blower to forcibly deliver a regulated flow of secondary combustion air to said first stage mixing zone. 12. The counter-flow drum mixer asphalt plant as in claim 6, said dust feeder comprising a tubular auger having a plurality of discharge openings along the length thereof to deliver fine additives and a pair of flexible shields suspended from said tubular auger along opposite sides of said discharge openings to direct fine additives downwardly to said asphaltic composition within said second stage mixing zone. 13. The counter-flow drum mixer asphalt plant as in claim 6 wherein said drying zone of said cylinder is equipped with a plurality of veiling flights mounted on the interior surface of said cylinder to transport aggregate material through said drying zone to said combustion zone and to create a curtain of falling aggregates in said drying zone with rotation of said cylinder, wherein said hot gas stream flows through the curtain of falling aggregates to heat and dry the aggregate material. 14. The counter-flow drum mixer asphalt plant as in claim 6, wherein said combustion zone of said cylinder is equipped with a plurality of spaced apart, nonveiling flights mounted on the interior surface of said cylinder within said combustion zone to transport aggregate material through said combustion zone and to admit RAP material from said recycle feeder directly into said combustion zone for exposure to radiant heat therein. 15. The counter-flow drum mixer asphalt plant as in claim 14, wherein said recycle feeder includes a collar circumscribing said cylinder and openings through said cylinder in registry with said collar whereby RAP material is introduced to said combustion zone through said spaced apart, nonveiling flights. 16. The counter-flow drum mixer asphalt plant as in claim 6 further comprising a secondary burner mounted adjacent said first end of said cylinder in contact with said hot gas stream discharged from the first end of said cylinder to elevate the temperature of said discharged hot gas stream prior to delivery to air pollution control equipment. 17. The counter-flow drum mixer asphalt plant as in claim 16 further comprising a temperature controller connected to said secondary burner to maintain said discharged hot gas stream prior to delivery to air pollution control equipment above its dew point temperature.
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이 특허에 인용된 특허 (38)
Musil Joseph E. (Ely IA), Apparatus for and methods of producing a hot asphaltic material.
Hawkins Michael (Kansas City MO) Schreter Robert E. (Roswell GA), Counter-flow asphalt plant with multi-stage combustion zone overlapping the mixing zone.
Farnham Robert E. (Naperville IL) Prill Fredric W. (North Aurora IL), Counterflow asphalt drum mixer producing less hydrocarbon emissions and a method used therein.
Garbelman David L. (Edmond OK) Minor William H. (Bethany OK) Shaw Arthur G. (Mustang OK), Method and apparatus for producing hot mix asphalt utilizing recyclable asphalt aggregate.
Mendenhall Robert L. (1770 Industrial Rd. Las Vegas NV 89102), Process for treating exhaust gaseous mixtures from directly exposing asphalt-aggregate compositions to hot gases.
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