Pyrolytic combustion apparatus and method

A method and apparatus for incinerating waste material and in particular, for incinerating particulate material resulting from the shredding of vehicles. The particulate material is fed to one end of a rotary drum, and is subjected in the drum to pyrolitic incineration in the absence of air, to generate combustible gases and a solid residue. The combustion gases and the residue are discharged from the drum to a discharge hood, where the solid residue is separated from the gases. The gases are then passed through a condenser to cool the gases to a temperature below 212.degree. F. to thereby condense water vapor and higher boiling point hydrocarbon gases to produce hydrocarbon liquid. The condensed water vapor and hydrocarbon liquid are separated from the lower boiling point hydrocarbon gases in a liquid-gas separator and the condensed water vapor and hydrocarbon liquid are discharged into a tank of water, where the hydrocarbon liquid will form a layer on the top of the water, and can subsequently be removed, while the lower boiling point hydrocarbon gases can be discharged to an afterburner to provide complete combustion of the combustible material in the gas.

BACKGROUND OF THE INVENTION 
The disposal of old automobiles and other vehicles has presented a serious 
environmental problem. One method of disposal is to subject the vehicles 
to a mechanical shredding operation, in which the entire vehicle is broken 
up into small particles or fragments which can range up to several inches 
in size. Ferrous metal fragments, as well as non-ferrous metal fragments, 
can be separated and the remaining material, which is substantially 
non-metallic, is often referred to as "fluff". The fluff consists of 
particles or fragments of materials, such as rubber, plastic, paint, 
insulation, glass and the like, and may contain up to 10% metal, mostly 
non-ferrous metals. 
The "fluff" has a very high BTU value due to the presence of large 
quantities of rubber, plastic, paints and the like. Due to its high BTU 
value and its non-homogeneous nature, the incineration of "fluff" is very 
difficult to control, and large volumes of corrosive and polluting gases 
are generated. Further, the presence of metals and glass in the "fluff" 
can result in the formation of slag at the high temperatures of 
incineration. 
Because of these problems, the "fluff" generated through the shredding of 
vehicles, has not been incinerated, but instead has been land-filled, and 
this presents serious environmental problems. 
SUMMARY OF THE INVENTION 
The invention is directed to a method and apparatus for incinerating waste 
material, and in particular, for incinerating "fluff" from the shredding 
of vehicles. 
In accordance with the invention, the waste material or "fluff" is fed by 
an auger to one end of a sealed rotary drum, where the waste material is 
subjected to pyrolitic decomposition in the absence of air to generate 
combustion gases and a solid residue. The combustion gases consist of low 
boiling point hydrocarbon gases such as methane, ethane, carbon dioxide, 
and the like, as well as higher boiling point hydrocarbon gases, along 
with water vapor. 
The combustion gases and solid residue are discharged from the downstream 
end of the drum to a discharge hood, where the solid residue is separated 
from the gases. 
The combustion gases are then passed through a condenser to cool the gases 
to a temperature below 212.degree. F. to cause condensation of the water 
vapor, as well as condensation of the higher boiling point hydrocarbon 
gases. The condensed liquid products along with the remaining combustion 
gases are discharged from the condenser to a liquid-gas separator. In the 
separator, the condensed products are fed into a tank of water, where the 
condensed hydrocarbons will collect as an upper oleophilic or oil layer 
and the oil layer can be continuously or intermittently removed from the 
tank, depending on the quantity of the oil that is deposited. 
The lower boiling point hydrocarbon gases are discharged from the 
liquid-gas separator, and can be delivered to an afterburner where air is 
mixed with the gases, and the mixture is combusted to provide complete 
combustion of the hydrocarbons. Alternately, the low boiling point 
hydrocarbon gases can be collected and subsequently used as a fuel. 
With the invention, the high BTU waste material is subjected to pyrolitic 
incineration in the absence of air to provide only partial combustion of 
the material and minimize the generation of fly ash. 
The high BTU components are separated from the combustion gases in the 
liquid gas separator through condensation and are not combusted, thus 
reducing the overall generation of heat from the combustion process and 
correspondingly reducing the volume of corrosive and polluting gases. 
Other objects and advantages will appear during the course of the following 
description.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENT 
The drawings illustrate an apparatus for incinerating waste material, and 
in particular to incinerating the substantially non-metallic residue or 
"fluff" from a vehicle shredding operation. In general, the "fluff" 
consists of small pieces or fragments, up to several inches in size, 
composed of materials such as rubber, plastic, insulation, paint, glass 
and the like. The fluff may also contain up to about 10% of metal, 
primarily non-ferrous metals. Because of the presence of the materials 
such as rubber, plastic and the like, the fluff has a very high BTU value, 
and cannot be incinerated normal procedures. 
The apparatus includes a generally cylindrical refractory lined furnace 1, 
which is mounted on a frame 2, and an inclined rotary drum 3 is mounted 
for rotation within furnace 1. 
The waste material to be incinerated is fed into the upper end of a hopper 
4 and conveyed from the lower end of the hopper tro the upper or high end 
of drum 3 by an auger feeder 5, as best seen in FIG. 2. Auger feeder 5 
includes a spiral flight 6 which is mounted on a central shaft 7 and one 
end of the shaft projects from the feeder 5 and is connected via a chain 
drive 8 to a motor and transmission unit 9 mounted on frame 2. With this 
arrangement, operation of the drive unit 9 will rotate the spiral flight 
to convey the waste material from hopper 4 into drum 3. The furnace, 
rotary drum and feeding mechanism can be similar to those described in 
U.S. Pat. No. 4,941,822. 
The waste material is subjected to pyrolitic incineration in drum 3, and 
thus the drum is substantially sealed so that the combustion takes place 
in the absence of air, other than air being brought in with the waste 
material through the auger feeder 5. 
To provide the sealed conditions, the upper end of the rotating drum 3 is 
closed off by an end wall 10, having a central opening 11 to receive the 
auger 5, as shown in FIG. 2. The rotating drum 3 is sealed to the fixed 
auger 5 through a seal mechanism 12 of the type described in U.S. Pat. No. 
4,941,822. The seal 12 permits the drum 3 to rotate relative to auger 5, 
but prevents the ingress of air at the joint therebetween. 
Drum 3 can be rotated within furnace 1 in the manner as described in U.S. 
Pat. No. 4,941,822. In this regard, a pair of idler rollers 13 are mounted 
on frame members 14 and rotatably support the lower or discharge end of 
drum 3. A second pair of rollers 15 are mounted for rotation on frame 
members 16 and engage a track 17 which extends circumferentially around 
the upper end of drum 3. The rollers 13 and 15 thus support drum 3 for 
rotation within furnace 1. 
To drive the drum, a sprocket 18 is secured to the outer surface of the 
projecting end of drum 3 adjacent track 17, and the sprocket is connected 
through a chain drive to a suitable motor and transmission unit, not 
shown, which is mounted on frame 2. Operation of the motor will rotate 
drum 3 within furnace 1. 
A group of fuel burners 20 are mounted in the lower end of furnace 1, and 
serve to supply a combustible mixture of gas fuel and air to the annular 
space 22 between drum 3 and furnace 1. The combustible gas mixture is 
ignited by a suitable ignition mechanism, and serves to heat the waste 
material which is being conveyed through drum 3. Burners 20 are generally 
used at the startup of the operation. Once the pyrolitic combustion has 
started, the heat generated by the combustion of the waste material will 
normally be sufficient to carry on the process without operation of 
burners 20. In practice, it is desirable to maintain the temperature in 
drum 3 at a value of about 1300.degree. to 1600.degree. F., and operation 
of burners 20, as well as the introduction of a coolant into the annular 
space between furnace 1 and drum 3 can be used to maintain the temperature 
at this range. The gases resulting from the combustion of the burner gas 
can be discharged from furnace 1 through a series of vents or flues 23. 
A plurality of longitudinal baffles, not shown, can be mounted in drum 3 as 
described in U.S. Pat. No. 4,941,822. As drum 3 rotates, the baffles will 
engage and lift the waste material to provide more uniform heating. 
As the waste material passes through drum 3 and is heated therein, partial 
combustion and pyrolitic decomposition will occur, resulting in the 
generation of combustible gases as well as a solid residue consisting of 
non-combustible material, such as metal, carbon, and the like. The 
combustible gases consist of a complex mixture of low boiling point 
hydrocarbon gases, such as methane, ethane, carbon dioxide, carbon 
monoxide, and the like, along with higher boiling hydrocarbon gases and 
water vapor. 
The combustion gases, as well as the solid residue, are discharged from the 
lower end of the inclined drum 3 into a discharge hood 24. As the drum 3 
rotates and hood 24 is fixed, a rotary seal 25 is provided to prevent the 
entry of air at the junction therebetween. Seal 25 is best shown in FIG. 
4, and consists of a radial flange 26 formed on the downstream end of drum 
3, which rides against an annular plate 27, formed of bronze or the like, 
which is mounted around an opening in hood 24. Flange 26 is urged against 
plate 27 by a series of rollers 28 that are mounted on shafts 29. The 
shaft 29 of each roller 28 is connected to a slide 30 that is mounted for 
sliding movement on rod 31. Rod 31 is attached to bracket 32 that is 
secured to hood 24. A spring 31 is connected between bracket 32 and slide 
30, and serves to urge the roller 28 against flange 26, thus providing a 
seal between the rotating drum flange 26 and the fixed plate 27 on hood 
24. 
The solid residue being discharged from drum 3 will fall downwardly within 
hood 24 and can be collected in a suitable collection site. In practice, a 
sealing mechanism can be incorporated with the lower end of hood 24 to 
discharge the collected solid residue either continuously or 
intermittently, and prevent the entry of air into hood 24. The combustion 
gases entering hood 24 are discharged through the upper end of the hood. 
Because of the high temperatures to which drum 3 is subjected in operation, 
the drum may expand by several inches longitudinally. To accommodate this 
expansion and contraction, hood 24 is mounted to move with drum 3. In this 
regard, a pair of cables 33 are suspended from frame members 34 that are 
located on either side of hood 24. The lower ends of cable 33 are 
connected to eyes 35 that are mounted on brackets 36 on either side of 
hood 24, as shown in FIG. 1. With this construction, hood 24 can move in a 
general horizontal path to accommodate expansion and contraction of drum 
3, and maintain the seal therebetween. 
The combustion gases being discharged from the upper end 38 of hood 24 are 
conducted through a conduit 39 to condenser 40. Conduit 39 can be formed 
in a pair of sections which are connected by a suitable expansion joint 
42, thus enabling the hood 24 to move with expansion and contraction of 
drum 3 while maintaining the connection to the condenser 40. 
In the condenser 40, the combustion gases are cooled to a temperature below 
212.degree. F., and generally in the range of about 90.degree. F. to 
175.degree. F. Cooling of the gases to this temperature range will result 
in the condensation of water vapor as well as the condensation of the 
higher boiling point hydrocarbon gases. The cooling can be achieved by 
introducing cooling water into contact with the gases in the condenser. As 
best shown in FIG. 5, cooling water in line 43 can be discharged through a 
series of jets or nozzles 44 into the condenser 40, and into contact with 
the combustion gases flowing through the condenser, thus cooling the gases 
to the aforementioned temperature range. 
The lower or downstream end of condenser 40 is connected to the central 
portion of a vertical liquid-gas separator 45. The condensed water vapor, 
as well as the condensed hydrocarbons, being discharged from condenser 40 
will flow downwardly in separator 45, while the remaining hydrocarbon 
gases will flow upwardly through the separator. 
As best shown in FIG. 5, the lower end portion of separator 45 extends into 
a tank 46 containing water, and the lower extremity of separator 45 is 
beneath the water level, indicated by 47. The condensed water vapor 
flowing into separator 45 will mix with the water in tank 46, while the 
condensed hydrocarbons, consisting of oils and/or tars, will collect as an 
oleophilic or oil layer 48 in the lower end of separator 45. As shown in 
FIG. 5, the liquid level in separator 45 will be higher than the liquid 
level in tank 46, due to the vacuum which is being drawn in the separator 
45. 
As a feature of the invention, the water in tank 46 can be used as a 
coolant in condenser 40. A line 49 connects the lower end of tank 46 to 
the suction side of a pump 50, while the discharge side of the pump is 
connected to line 43. With this construction, operation of the pump will 
deliver water to the condenser 40. 
Depending on the amount of oil or liquid hydrocarbons that are collected in 
separator 45, the oil can be continuously or periodically removed. This 
can be accomplished by connecting a siphon line 51 to the separator 45 at 
the level of the oil layer 48. As shown in FIG. 5, the siphon line can 
extend outwardly through a suitable opening in the wall of tank 46. 
The non-condensed hydrocarbon gases are discharged from the upper end of 
separator 45 through a conduit 52, and conduit 52 is connected through a 
flexible joint 53 to a conduit 54 that is connected to the suction side of 
a blower 55. The discharge side of blower 55 is connected via conduit 56 
to the lower end of an afterburner 57. Operation of blower 55 provides the 
draft for drawing the gases through the entire system. 
Afterburner 57 is of conventional construction, and serves to provide 
substantially complete combustion of the combustible material in the gas. 
In this regard, a fuel burner 58 and air blower 59 can be connected to the 
afterburner. The air will mix with the combustion gas to provide a 
combustible gas mixture which is then ignited and fully combusted through 
operation of burner 58, and the residual gas is discharged from 
afterburner 57 through stack 60. 
Alternately, the low boiling point hydrocarbon gases, such as methane, 
ethane, and the like, being discharged from separator 45, can be collected 
and subsequently used as a fuel. 
With the construction of the invention, the high BTU hydrocarbon components 
are removed from the combustion gas by condensation and are not combusted. 
This substantially reduces the overall heat generated by the incineration 
process, and also decreases the volume of corrosive and hazardous gases 
that are evolved from the process.