Device for conveying waste in a pyrolysis reactor

A device for conveying waste includes a waste feed chute. A stationary conveyor pipe is connected to the waste feed chute and has a sealed-off end and a housing with a nonround cross section defining a longitudinal direction. A screw conveyor is disposed in the longitudinal direction of the conveyor pipe. A motor drives the screw conveyor. A pyrolysis reactor into which the conveyor pipe discharges, defines a first space between the housing of the conveyor pipe and the pyrolysis reactor. The pyrolysis reactor has an inlet end and a longitudinal axis about which the pyrolysis reactor is rotatable. An inlet tube in which the sealed-off end of the conveyor pipe is disposed, defines a second space between the inlet tube and the conveyor pipe. The inlet tube communicates with the inlet end of the pyrolysis reactor and has a smaller cross section than the pyrolysis reactor. At least one supply line leads from outside into the pyrolysis reactor. The at least one supply line is disposed in the first space and is extended through the second space.

CROSS-REFERENCE TO RELATED APPLICATION 
This application is a Continuation of International Application Serial No. 
PCT/DE94/01058, filed Sep. 14, 1994. 
BACKGROUND OF THE INVENTION 
Field of the Invention 
The invention relates to a device for conveying waste, in which a waste 
feed chute is connected to a conveyor pipe, in the longitudinal direction 
of which a screw conveyor, drivable by a motor, is disposed, and in which 
the conveyor pipe discharges into a pyrolysis reactor, in particular into 
a low-temperature carbonization combustion drum that is rotatable about 
its longitudinal axis. The conveyor pipe is used for thermal waste 
disposal, especially according to the low-temperature carbonization 
combustion process. 
The so-called low-temperature carbonization combustion process has become 
known in the field of waste disposal. The process and a system operating 
according to the process for thermal waste disposal are described, for 
instance, in Published European Patent Application 0 302 310 A1, as well 
as in German Published, Non-Prosecuted Patent Application DE 38 30 153 A1 
corresponding partly to Published European Patent Application 0 360 052 
A1. The system for thermal waste disposal according to the low-temperature 
carbonization combustion process includes a pyrolysis reactor and a 
high-temperature combustion chamber as its essential components. The 
pyrolysis reactor converts the waste being fed through a waste conveyor of 
the type referred to at the outset, into low-temperature carbonization gas 
and pyrolysis residue. The low-temperature carbonization gas and the 
pyrolysis residue are then delivered, after suitable preparation, to the 
burner of the high-temperature combustion chamber. That produces molten 
slag, which can be removed through an outlet and which is in vitrified 
form after it cools down. The flue gas being produced is sent through a 
flue gas line to a chimney serving as an outlet. A waste heat steam 
generator acting as a cooling device, a dust filter system, and a flue gas 
cleaning system, in particular, are built into the flue gas line. There is 
also a gas compressor in the flue gas line, which is disposed directly at 
the outlet of a flue gas scrubber system and can be constructed as a 
suction draft blower. The built-in gas compressor serves to carry gas 
through the system and in particular serves to maintain a negative 
pressure, however slight, in the pyrolysis drum. As a result of that 
negative pressure, low-temperature carbonization gas is prevented from 
passing out to the environment through ring seals of the pyrolysis drum. 
Through the use of the conveying device, waste of various kinds, such as 
comminuted household garbage, industrial waste similar to household 
garbage, and comminuted bulk trash, as well as dewatered sludge, is fed to 
the low-temperature carbonization drum. 
It has been found that in a low-temperature carbonization combustion 
system, the conveying device for waste can be blocked or destroyed if 
excessively large particles of waste drop from the waste feed chute into a 
coil of the conveying screw. However, the avoidance of blockage of the 
conveying screw is necessary for continuous operation. After all, as a 
rule, new trash or waste is supplied continuously. In order to provide 
problem-free conveying of the waste it is also necessary that the waste 
not stick to the screw or rotate with the screw coil. In order to achieve 
that, it is usual in conveying screws to place strips on a housing of its 
wall that protrude into an interstice between the conveying screw and the 
housing. When the conveying screw rotates, the material to be conveyed is 
prevented from rotating with the screw by the strips on the screw. 
However, such strips are subject to severe wear. 
German Published, Non-Prosecuted Patent Applications DE 38 30 151 A1, DE 38 
30 152 A1 and DE 38 30 153 A1, together corresponding to Published 
European Patent Application 0 360 052 A1, disclose pyrolysis reactors with 
a heater for waste, in which supply lines are provided with outlet nozzles 
for air on the end for the sake of direct heating of the waste in the 
low-temperature carbonization drum. Those supply lines are extended 
through a hot gas housing on the low-temperature carbonization drum. The 
known structures require special and therefore expensive sealing 
provisions. 
SUMMARY OF THE INVENTION 
It is accordingly an object of the invention to provide a device for 
conveying waste in a pyrolysis reactor, which overcomes the 
hereinafore-mentioned disadvantages of the heretofore-known devices of 
this general type and with which it is possible to lay at least one supply 
line that is intended to lead from the outside into the pyrolysis reactor, 
with comparatively little effort or expense. 
With the foregoing and other objects in view there is provided, in 
accordance with the invention, a device for conveying waste, comprising a 
waste feed chute; a stationary conveyor pipe being connected to the waste 
feed chute and having a sealed-off end and a housing with a nonround cross 
section defining a longitudinal direction; a screw conveyor disposed in 
the longitudinal direction of the conveyor pipe; a motor for driving the 
screw conveyor; a pyrolysis reactor, in particular a low-temperature 
carbonization drum, into which the conveyor pipe discharges, defining a 
first space between the housing of the conveyor pipe and the pyrolysis 
reactor, the pyrolysis reactor having an inlet end and a longitudinal axis 
about which the pyrolysis reactor is rotatable; an inlet tube in which the 
sealed-off end of the conveyor pipe is disposed, defining a second space 
between the inlet tube and the conveyor pipe, the inlet tube communicating 
with the inlet end of the pyrolysis reactor and having a smaller cross 
section than the pyrolysis reactor; and at least one supply line leading 
from outside into the pyrolysis reactor, the at least one supply line 
being disposed in the first space and being extended through the second 
space. 
Blockage of the conveying screw should be avoided as much as possible. In 
order to prevent the waste from rotating with the conveying screw, a 
deflection space may be provided between the conveying screw and the 
housing. This space is formed by ensuring that from the longitudinal axis 
of the conveying screw, measured outward at right angles to the 
longitudinal axis, a variably large spacing remains free between the 
largest radius of the conveying screw and the housing wall, depending on 
the radial direction in which measurement is taken. This assures that the 
conveyed waste can come loose from the conveying screw from time to time, 
so that it does not rotate with the conveying screw. 
Advantageously, no strips need be attached to the inner wall surface of the 
housing as was previously usual for preventing the material from rotating 
with the conveying screw. While such strips are subject to major wear, the 
present conveying device can be operated largely with little wear. The 
housing has a circular cross section, for example. 
In accordance with another feature of the invention, the housing has a 
polygonal cross section. This polygonal cross section may be a 
trough-shaped cross section, with a lower polygonal part and an upper 
rectangular part. It may also be a polygon with sides of equal length. 
These embodiments also have the effect of preventing the waste to be 
conveyed from rotating with the conveying screw. 
The supply line or lines can serve any possible purposes, such as supplying 
air to the pyrolysis reactor. 
The conveying device can be used at the inlet and/or the outlet of the 
pyrolysis reactor. 
In accordance with a further feature of the invention, the inlet tube has 
an end with a slide seal. 
In accordance with an added feature of the invention, there is provided a 
chamber for the passage of heating gas being slidingly secured to the 
inlet tube. 
In accordance with an additional feature of the invention, the supply line 
transports a medium selected from the group consisting of inert gas, 
water, water vapor and air. 
In accordance with yet another feature of the invention, the at least one 
supply line has an outlet nozzle in the pyrolysis reactor. 
In accordance with yet a further feature of the invention, the screw 
conveyor has segments of differing pitch. 
With the objects of the invention view there is also provided, in 
accordance with the invention, in combination with a pyrolysis reactor 
being rotatable about its longitudinal axis and having an interior, a 
conveying device for feeding waste into and discharging waste out of the 
pyrolysis reactor, comprising an inlet tube being secured to the pyrolysis 
reactor, having a smaller cross section than the pyrolysis reactor, being 
rotatable with the pyrolysis reactor about its longitudinal axis, and 
having an end; a sealing ring secured to the end of the inlet tube; a 
stationary conveyor pipe protruding into the inlet tube and having an 
outer periphery and a housing with a nonround cross section defining a 
space between the housing and the inlet tube; a counterpart ring for the 
sealing ring, the counterpart ring being secured to the outer periphery of 
the conveyor pipe; and at least one extraction and supply line leading 
from outside through the space into the interior of the pyrolysis reactor. 
Other features which are considered as characteristic for the invention are 
set forth in the appended claims. 
Although the invention is illustrated and described herein as embodied in a 
device for conveying waste in a pyrolysis reactor, it is nevertheless not 
intended to be limited to the details shown, since various modifications 
and structural changes may be made therein without departing from the 
spirit of the invention and within the scope and range of equivalents of 
the claims. 
The construction and method of operation of the invention, however, 
together with additional objects and advantages thereof will be best 
understood from the following description of specific embodiments when 
read in connection with the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to the figures of the drawings in detail and first, 
particularly, to FIG. 1 thereof, there is seen a conveying device 2 for 
waste A, in which a drop chute or waste feed chute 4 is connected through 
a disconnectable securing device 6 to a stationary conveyor pipe or 
channel 8. The conveyor pipe 8 in this case is constructed as a conveying 
screw trough. The conveyor pipe 8 has a housing 8a with a preferably 
polygonal cross section, as is shown in FIG. 2. A longitudinal axis of the 
housing 8a is shown at reference numeral 9. The conveyor pipe 8 discharges 
into a pyrolysis reactor 10, which in the present case is a 
low-temperature carbonization drum rotating about its longitudinal axis 
11. The low-temperature carbonization drum 10 is equipped with a 
relatively large number of heating tubes 12 that are parallel to the 
longitudinal axis 11. The heating tubes 12, only two of which are shown in 
FIG. 1 and 48 of which are shown in FIG. 2, are charged with hot gas h, 
such as hot air. The heating tubes 12 are firmly fastened in an end ring 
12s, which is concentrically adjoined by an inlet tube 13. An end of the 
conveyor pipe 8 is located concentrically within this inlet tube 13. As 
will be described below, provision is made at that point for good sealing. 
The interior of the conveyor pipe 8, which in normal operational is 
stationary, contains a conveying screw or worm 14, having a longitudinal 
axis 15 which extends in the longitudinal direction thereof. A shaft 16 of 
the conveying screw 14 is driven through a gear 18 by a motor 20. The 
waste feed chute 4 is disposed laterally of or vertically above the 
conveyor pipe 8, on its end. A fill opening for the waste is indicated by 
reference numeral 22, and a discharge opening is indicated by reference 
numeral 24. 
When waste A is conveyed from the drop chute 4 to the low-temperature 
carbonization drum 10, it is necessary both to prevent oxygen from the air 
from reaching the low-temperature carbonization drum 10 from the inlet 
opening 22 through the discharge opening 24, as well as to prevent 
low-temperature carbonization gas from reaching the environment from the 
low-temperature carbonization drum 10 through the fill opening 22, in 
countercurrent with the conveyed waste A. In order to do so, a middle 
portion 14a of the conveying screw 14 has a lesser pitch than the 
remainder of the conveying screw 14 or an initial portion 14b. As a 
result, the conveyed waste A is more severely compacted in the region of 
this middle portion 14a than in the other regions, and as a result in the 
region of the portion 14a of the conveying screw 14 virtually the entire 
portion of the space in the housing 8a of the conveyor pipe 8 is filled 
with the waste A. The conveyed waste A itself seals the housing 8a in 
gas-tight fashion at that location. Air cannot flow from the fill opening 
22 to the discharge opening 24, and low-temperature carbonization gas 
cannot flow in the opposite direction. The conveying screw 14 again has a 
greater pitch downstream, as seen in the conveying direction of the 
compacting zone, which is located in the region of the portion 14a of the 
conveying screw 14. As a result, the packing of the waste A, which packing 
extends over the entire cross section of the conveyor pipe 8, is loosened 
up again. 
An important factor is that because of the geometrical configuration, at 
least one extraction and supply line 32 leading from the outside into the 
pyrolysis reactor 10 is disposed in a first space 30 between the housing 
8a of the conveyor pipe 8 and the pyrolysis reactor 10. In the present 
case, as is shown in FIG. 2, there are three supply lines 32. In this case 
a second space within the first space 30 is located between the housing 8a 
and the inlet tube 13. The supply lines 32 are located in "free corners" 
outside the housing 8a. The supply lines 32 are intended, for example, for 
introducing air 1, inert gas, water, or water vapor, which may be 
superheated. The air 1 being introduced can be used for partial combustion 
of low-temperature carbonization gas in the pyrolysis reactor 10. Two air 
outlet nozzles or combustion nozzles on the supply line 32 are shown at 
reference numeral 35 in FIG. 1. The waste in the pyrolysis reactor is 
heated and dried directly by introducing superheated steam. 
Another significant factor is good sealing of the pyrolysis reactor 10 from 
the outside. To that end, a slide ring seal 40 is disposed on the end of 
the inlet tube 13. The slide ring seal 40 includes a co-rotating slide 
ring 42 and a stationary counterpart ring 44, both of which may be made of 
steel. The counterpart ring 44 is firmly attached to a ring 46, which is 
welded to the housing 8a with the aid of a weld seam 48. 
In order to enable closing off the housing 8a of the conveyor pipe 8 in 
gas-tight fashion through the use of the conveyed waste A, the conveying 
device 2 should be operated fully filled. In order to prevent relatively 
large, hard pieces of waste A from blocking the conveying screw 14, 
variously located and configured deflection spaces 34 for such relatively 
large pieces may be provided inside the housing 8a, because of the 
geometrical shaping. In other words: the conveyor pipe 8 can have not 
merely the polygonal cross section shown but other cross sections instead. 
When the conveying screw 14 is rotating, the relatively large pieces to be 
conveyed are forced into these deflection spaces 34 and are transported 
along with the longitudinally moved waste A in the deflection spaces 34, 
so that they cannot block the conveying screw 14. The deflection spaces 34 
as a rule are located above or to the side of the conveying screw 14. 
In FIG. 1, the waste A in the rotating low-temperature carbonization drum 
is heated indirectly by the hot gas h through the use of the heating tubes 
12. This hot gas h is fed into the low-temperature carbonization drum 10 
through a non-illustrated stationary hot-gas inlet housing. The parallel 
heating tubes 12 are secured at one end to a bottom wall of the drum. The 
other end is secured to the end ring or bottom wall 12s, which forms a 
portion of a wall of a "cold" hot-gas outlet housing 50. From this housing 
50, the hot gas h enters an outlet. In order to seal off the hot-gas 
outlet housing 50 from the rotating drum or tube 10 and from the inlet 
tube 13, respective ring seals 52 and 54 are provided. Non-illustrated 
Ring seals are correspondingly provided to seal off the hot-gas inlet 
housing. A non-illustrated discharge tube is extended from the interior of 
the low-temperature carbonization drum 10, or more precisely from the 
"hot" tube bottom, into the interior of a stationary discharge device. The 
low-temperature carbonization material entering this discharge device 
through the discharge tube is split, in the discharge device, into 
low-temperature carbonization gas and residue. The latter can be split and 
sorted out into various combustible and inert fractions through the use of 
a suitable non-illustrated device, according to the low-temperature 
carbonization combustion process, before the combustible portion is taken 
for combustion in a non-illustrated high-temperature combustion chamber. 
It should also be pointed out that instead of or in addition to at least 
one supply line 32, it is naturally possible for an extraction line to 
also be disposed in the space 30 between the housing 8a of the conveyor 
pipe or channel 8 and the pyrolysis reactor 10 (or its inlet tube 13). 
This extraction line can serve, for instance, as a suction extraction tube 
for removing water vapor from the interior of the pyrolysis reactor 10. It 
should also be noted that a supply and/or extraction line 32 may be 
disposed at the outlet of the pyrolysis reactor 10, instead of at the 
inlet, by using an outlet tube that corresponds to the inlet tube 13.