Abstract:
An asphalt based material recycling system and method is used to recycle asphalt materials, such as asphalt shingles and tar paper that include granules, fibers or other particles. The asphalt material is simultaneously heated and milled in a heated milling apparatus, such as a heated ball mill, to reduce the asphalt material including granules to a fine mesh in suspension in liquid asphalt. Excess moisture is removed from the asphalt material being recycled by continuously venting the heated milling apparatus. The heated milling apparatus preferably includes a rotatable milling vessel rotated at an acute angle with respect to the horizontal plane and having an opening that provides continuous venting. The shape of the milling vessel allows the liquid level inside the milling vessel to have a liquid head above the outlet region of the milling vessel, for facilitating milling. The rotatable milling vessel includes a plurality of mixing members, such as rods or paddles, extending from an interior surface to enhance milling and to pull the asphalt material being recycled under and into the liquid slurry. The asphalt material recycling system further includes a filter apparatus for filtering reduced asphalt and removing foreign objects therefrom.
Abstract:
An apparatus for the treatment of 100% reclaimed asphaltic pavement (RAP) uses low temperatures and no direct radiation from a burner flame to the RAP. The RAP is first heated in a counter flow drum which is supplied with hot combusting gases generated by a remote low NOx burner. The temperature of the drum input gases is preferably around 1100 degrees F and the output temperature of the gases may be 100 degrees F or less greater than the input temperature of the RAP. The RAP may be heated with a microwave oven to raise the RAP to a final temperature, although this step is not absolutely necessary in the counterflow design of this invention.
Abstract:
A combination continuous/batch asphalt plant includes mechanisms and controls which permit it to be hot-stopped when operating in the continuous mode.
Abstract:
A dryer drum coater has an internal recirculation cylinder for promoting the recirculation of combustion products so as to entrain and incinerate blue smoke formed when heated and dried virgin aggregate is mixed with other asphaltic products such as RAP and/or liquid asphalt in the dryer drum coater. The recirculation cylinder acts to extend and strengthen natural eddy currents formed during operation of the coater such that combustion product recirculation which would normally extend only in the end area of the flame extends far enough toward the base of the flame to entrain the blue smoke and to draw the blue smoke into the base area of the flame. The cylinder may comprise a refractory lined stainless steel shell or may be formed from tee flights of the type used in the combustion zones of dryer drum coaters.
Abstract:
An asphalt recycling apparatus includes a combustion drum which is rotatably mounted in an enclosure; the outer surface of the drum is covered with an insulating material and the enclosure includes a storage member for a gas fueled burner for treating waste asphalt pieces in the combustion drum; the enclosure is provided with a pair of doors disposed on the front side of the casing and the combustion drum is mounted for tilting movement substantially about a horizontal axis; the pair of doors are provided with a support for the combustion burner so as to direct the flame of the burner to an opening in the combustion drum; a chute door is disposed below the front opening of the casing and hinged to the casing.
Abstract:
A combustion chamber having improved heating efficiency and reduced NO.sub.x emissions includes a reduced diameter throat and a stepped configuration within the chamber. The chamber configuration encourages efficient combustion to reduce NO.sub.x production by promoting the formation of eddy currents within the chamber. A method for increasing heating efficiency and reducing NO.sub.x production is provided and involves passing combustion gases through such a combustion chamber.
Abstract:
An apparatus is disclosed which is adapted to heat and dry stone aggregate useful in the production of asphalt paving, and which also has the ability to incinerate contaminated soil. The apparatus comprises a rotary drum for heating and drying the stone aggregate, and a separate rotary incinerator for incinerating the soil. The incinerator includes an outlet housing for withdrawing the incinerated soil and selectively conveying the soil so as to be mixed with the heated and dried aggregate, or delivered to a separate location. Further, the incinerator has an exhaust duct for conveying the gaseous products of combustion from the incinerator into the rotary drum, so that any volatile hydrocarbons contained in the gaseous products of combustion from the incinerator are effectively incinerated before being discharged to the atmosphere.
Abstract:
A method for treating asphalt roofing shingles to be used for recycling in an asphalt plant which mixes asphalt roofing shingles with between about 15% and 50% by weight of a carrier aggregate. The aggregate is fed into a shredder with the shingles or is otherwise mixed with the comminuted shingles to form a recyclable asphaltic material which may be easily stored and transported, and which may also be used in the preparation of asphalt paving composition.
Abstract:
An asphalt drum drying and mixing plant capable of using recycled pavement aggregate material includes two interacting drums, each being heated to different temperatures. A first drum is a parallel flow drying and mixing drum. The recycled material is introduced at the intake or feed end of this first drum and dried and heated to a comparatively low temperature in a first region of the first drum. A burner of relatively lower heat generation capacity furnishes heated gases. The recycled material is protected by supplying the gases through a cylindrical combustion chamber within which the fuel is completely burned such that no luminous gases enter the drum and contact the recycled material. A second, adjacent region of the parallel flow drum is the mixing region. The recycled material is transferred to the mixing region with the close control over the temperature at which the material enters the mixing region. The parallel flow drum also has an intermediate feed chute through which virgin aggregate material is added. The virgin aggregate is heated in a counterflow drum to a temperature higher than the recycled material and the temperature of the final mix is controlled by changing the temperature of the virgin material. The exhaust from the mixing region is introduced as secondary air into the counterflow drum burner assembly. From the counterflow drum all gases are passed to a cleaning system including a cyclone separator and a baghouse filter. From the cyclone separator and the baghouse filter separated material and fines are routed into the mixing region together with liquid asphalt cement.