Asphalt production plant having a two-burner dryer with increased exhaust capacity

An apparatus for producing asphalt, the apparatus comprising:

• a dryer drum having an inlet end, a discharge end, an inner periphery, and a longitudinal axis, the longitudinal axis extending between the inlet end and the discharge end thereof;
• means for rotating the dryer drum about the longitudinal axis thereof;
• parallel burner means for producing a parallel flame in the dryer drum, the parallel flame extending from the inlet end of the dryer drum toward the discharge end of the dryer drum;
• counterflow burner means for producing a counterflow flame in the dryer drum, the counterflow flame extending from the discharge end of the dryer drum toward the inlet end of the dryer drum;
• aggregate feed means for conveying aggregate into the inlet end of the dryer drum;
• means for mixing the heated aggregate discharging from the dryer drum with a bituminous liquid to produce asphalt mix, the means for mixing having an inlet end and a discharge end;
• means for transferring aggregate from the discharge end of the dryer drum into the inlet end of the means for mixing;
• means for discharging asphalt mix from the discharge end of the means for mixing;
• a dust chamber surrounding a medial dust section of the dryer drum, the dust section of the dryer drum having a plurality of slots therethrough;
• a plurality of angle plates mounted to the dust section of the dryer drum, each angle plate covering one of the slots through the dust section of the dryer drum and having a solid side and a perforated side;
• a return duct extending between the means for mixing and the dryer drum;
• end
• an exhaust system communicating with the dust chamber and having an exhaust fan for drawing exhaust gases out of the dryer drum and into the exhaust system, wherein the exhaust fan draws exhaust gases out of the means for mixing through the return duct and into the dryer drum to incinerate exhaust gases from the means for mixing in the dryer drum;
• wherein the apparatus is characterized further to include a plenum connected to the dryer drum and communicating with the annulus between the counterflow combustion chamber and the interior surface on the dryer drum, and
• wherein said return duct communicates with said plenum, whereby the exhaust gas from the means for mixing contacts the hot gases from the counterflow burner downstream from the counterflow combustion chamber.

An apparatus for producing asphalt, the apparatus comprising:

• a dryer drum having an inlet end, a discharge end, an inner periphery, and a longitudinal axis, the longitudinal axis extending between the inlet end and the discharge end thereof;
• means for rotating the dryer drum about the longitudinal axis thereof;
• parallel burner means for producing a parallel flame in the dryer drum, the parallel flame extending from the inlet end of the dryer drum toward the discharge end of the dryer drum;
• counterflow burner means for producing a counterflow flame in the dryer drum, the counterflow flame extending from the discharge end of the dryer drum toward the inlet end of the dryer drum;
• aggregate feed means for conveying aggregate into the inlet end of the dryer drum;
• means for mixing the heated aggregate discharging from the dryer drum with a bituminous liquid to produce asphalt mix, the means for mixing having an inlet end and a discharge end;
• means for transferring aggregate from the discharge end of the dryer drum into the inlet end of the means for mixing;
• means for discharging asphalt mix from the discharge end of the means for mixing;
• a dust chamber surrounding a medial dust section of the dryer drum, the dust section of the dryer drum having a plurality of slots therethrough;
• a plurality of angle plates mounted to the dust section of the dryer drum, each angle plate covering one of the slots through the dust section of the dryer drum and having a solid side and a perforated side;
• a return duct extending between the means for mixing and the dryer drum;
• and
• an exhaust system communicating with the dust chamber and having an exhaust fan for drawing exhaust gases out of the dryer drum and into the exhaust system, wherein the exhaust fan draws exhaust gases out of the means for mixing through the return duct and into the dryer drum to incinerate exhaust gases from the means for mixing in the dryer drum;
• wherein the apparatus is characterized further to include a plenum connected to the dryer drum and communicating with the annulus between the parallel flow combustion chamber and the interior surface on the dryer drum, and
• wherein said return duct communicates with said plenum, whereby the exhaust gas from the means for mixing contacts the hot gases from the parallel flow burner downstream from the parallel flow combustion chamber.

An asphalt production plant comprising:

• a rotatable dryer drum having an inlet end, a discharge end and an internal passageway extending between the inlet end and the discharge end thereof, said dryer drum being adapted to urge aggregate material through the internal passageway from the inlet end to the discharge end thereof;
• a first burner positioned within said dryer drum to direct a first stream of hot gases into the internal passageway of said dryer drum from the inlet end toward the discharge end of said dryer drum;
• a second burner positioned within said dryer drum to direct a second stream of hot gases into the internal passageway of said dryer drum from the discharge end toward the inlet end of said dryer drum;
• a dust chamber circumscribing a medial section of said dryer drum and communicating with the internal passageway of said dryer drum to receive exhaust gases from said first and second burners;
• exhaust means, communicating with said dust chamber, for drawing the first burner exhaust gases and the second burner exhaust gases out of said dryer drum through said dust chamber;
• mixing means for coating aggregate material with a bituminous liquid to produce asphalt product, said mixing means communicating with the discharge end of said dryer drum to receive aggregate material from said dryer drum;
• and
• flow control means for adjusting the relative proportion of first burner exhaust gases and second burner exhaust gases being drawn out of said layer drum by said exhaust means.

An asphalt production plant comprising:

• a rotatable dryer drum having an inlet end, a discharge end and an internal passageway extending between the inlet end and the discharge end thereof, said dryer drum being adapted to urge aggregate material through the internal passageway from the inlet end to the discharge end thereof;
• a first burner positioned within said dryer to direct a first stream of hot gases into the internal passageway of said dryer drum from the inlet end toward the discharge end of said dryer drum;
• a second burner positioned within said dryer drum to direct a second stream of hot gases into the internal passageway of said dryer drum from the discharge end toward the inlet end of said dryer drum;
• a dust chamber circumscribing a medial section of said dryer drum and communicating with the internal passageway of said dryer drum to receive exhaust gases from said first and second burners;
• exhaust means, communicating with said dust chamber, for drawing the first burner exhaust gases and the second burner exhaust bases out of said dryer drum through said dust chamber;
• and
• mixing means for coating aggregate material with a bituminous liquid to produce asphalt product, said mixing means communicating with the discharge end of said dryer drum to receive aggregate material from said dryer drum;
• wherein said mixing means comprises a rotatable mixer drum having an inlet end, a discharge end and an internal passageway extending from the inlet end to the discharge end thereof.

An asphalt production plant comprising:

• a rotatable dryer drum having an inlet end, a discharge end and an internal passageway extending between the inlet end and the discharge end thereof, said dryer drum being adapted to urge aggregate material through the internal passageway from the inlet end to the discharge end thereof;
• a first burner positioned within said dryer drum to direct a first stream of hot gases into the internal passageway of said dryer drum from the inlet end toward the discharge end of said dryer drum;
• a second burner positioned within said dryer drum to direct a second stream of hot gases into the internal passageway of said dryer drum from the discharge end toward the inlet end of said dryer drum;
• a dust chamber circumscribing a medial section of said dryer drum and communicating with the internal passageway of said dryer drum to receive exhaust gases from said first and second burners;
• exhaust means, communicating with said dust chamber, for drawing the first burner exhaust gases and the second burner exhaust gases out of said dryer drum through said dust chamber;
• mixing means for coating aggregate material with a bituminous liquid to produce asphalt product, said mixing means communicating with the discharge end of said dryer drum to receive aggregate material from said dryer drum;
• and
• mixer exhaust means, communicating with said mixing means and said dryer drum, for drawing exhaust gases out of said mixing means and into said first burner of said dryer drum to incinerate particles entrained in the exhaust gases from said mixing means.

An asphalt production plant comprising:

• a rotatable dryer drum having an inlet end, a discharge end and an internal passageway extending between the inlet end and the discharge end thereof, said dryer drum being adapted to urge aggregate material through the internal passageway from the inlet end to the discharge end thereof;
• a first burner positioned with said dryer drum to direct a first stream of hot gases into the internal passageway of said dryer drum from the inlet end toward the discharge end of said dryer drum;
• a second burner positioned within said dryer drum to direct a second stream of hot gases into the internal passageway of said dryer drum from the discharge end toward the inlet end of said dryer drum;
• a dust chamber circumscribing a medial section of said dryer drum and communicating with the internal passageway of said dryer drum to receive exhaust gases from said first and second burners;
• exhaust means, communicating with said dust chamber, for drawing the first burner exhaust gases and the second burner exhaust gases out of said dryer drum through said dust chamber;
• mixing means for coating aggregate material with a bituminous liquid to produce asphalt product, said mixing means communicating with the discharge end of said dryer drum to receive aggregate material from said dryer drum;
• and
• mixer exhaust means, communicating with said mixing means and said dryer drum, for drawing exhaust gases out of said mixing means and into said second burner of said dryer drum to incinerate particles entrained in the exhaust gases from said mixing means.