CN102803851A - Method and apparatus for continuously operating a pyrolysis reactor - Google Patents

Abstract

Method and device for continuously operating a pyrolysis reactor, with which method and device oxygen or any gas mixture containing oxygen, such as air, is excluded or prevented from flowing into the interior of the reactor during operation of said reactor, the reactor containing a supply duct for material for pyrolysis, means for conveying the material through said supply duct, the pyrolysis reactor having the means required for performing the pyrolysis isolation, means for removing gases released during the pyrolysis process and means for removing residual products, such as residues. The material in the supply conduit is fed by the first screw conveyor to a ramp in the conduit and to at least one further second screw conveyor in the feed conduit, which is connected to the supply conduit, wherein the second conveyor is driven at a lower speed than the first conveyor.

Description

Method and apparatus for continuously operating a pyrolysis reactor

technical field

The present invention relates to a method and a device for excluding and preventing the flow of oxygen or any gas mixture containing oxygen, such as air, into the reactor interior of a pyrolysis reactor, which is designed for continuous operation. The reactor contains a feed conduit for the material (e.g. plastic or rubber) used for pyrolysis, means for conveying this material through the feed conduit, the pyrolysis reactor itself, with the means required for pyrolysis isolation, for removing Mechanism for the gases released during the pyrolysis process and for the removal of residual products such as oil residues and residues.

Background technique

Gas generators for isolating combustible materials are a well known phenomenon, especially in the form used before and for example they are still used in certain factories for the production of domestic gas. The basic concept is the same, i.e. anaerobic isolation at increased temperature, and treatment of released gases and remaining products. However, it is the case that so far, as has been determined from exhaustive investigations, no one has hitherto succeeded in producing a pyrolysis reactor which operates practically continuously. In this unfortunate case, air or free oxygen is inadvertently brought into contact with the material undergoing pyrolysis, which inevitably leads to an explosion and fire. Basic textbook physics teaches that combustion (more generally: fire) needs to meet three conditions: first, proximity to the combustible material, second, reaching the ignition temperature of the combustible material, and third, having the required amount of free oxygen. Then, what happens in the pyrolysis reactor or gas generator? The answer is that the conditions must be created for an anaerobic process, more precisely a process in which all conditions for combustion exist except for the feed of free oxygen. Because no one has succeeded in producing a gas generator for the continuous pyrolysis of combustible materials, the designs that have worked so far are characterized in that they must be operated in batches, that is, the pyrolysis reactor is loaded with a set of pyrolyzable materials that The gases released during this process are then disposed of while being heated in the absence of oxygen. During the pyrolysis process, the pyrolysis reactor is hermetically sealed completely to seal the explosion process. Prolonged cooling is thereafter required to bring the temperature in the gas generator down to a level at which the residue remaining after pyrolysis does not ignite spontaneously upon the entry of free oxygen when the pyrolysis reactor is opened. This is not (and was not) a particularly good process, especially since it involves a lot of processing related to loading, heating and cooling. Energy efficiency is not good either.

Contents of the invention

It is therefore an important object of the present invention to propose a method and a device which, irrespective of the continuous supply of material, enables the feed conduit to the pyrolysis reactor to ensure the feeding of oxygen or air into the pyrolysis reactor while the continuous pyrolysis process takes place.

This object is achieved by a method and a device according to the invention, wherein the material in the feed duct is fed by a first screw conveyor towards a ramp in the duct and also towards a second screw conveyor in at least one feed duct, said feed A conduit is connected to the supply conduit, wherein the second conveyor is driven at a lower speed than the first conveyor.

According to a further developed design of the invention, the material for pyrolysis is fed by a first screw conveyor to a unit of two screw conveyors rotating in the same direction. This enables the material used for pyrolysis to be compressed such that all air and oxygen bound by it is pushed away. The compression is advantageous and the advancement of the material is simple since the aforementioned screw conveyors rotate in exactly the same direction.

According to a further developed design of the invention, the respective screws in a unit comprising two screw conveyors are driven at different speeds. This enables a higher degree of compression to be achieved, thus providing an even better seal than in this case. In this particular case, the screw conveyor with the highest speed in said unit with two such conveyors is also driven at a lower speed than the first screw conveyor.

This prevents suction pockets from being created, which at least technically result in air being sucked into the pyrolysis chamber at a pressure lower than ambient atmospheric pressure.

During a continuous pyrolysis process of the type described in the opening description, according to a further developed design of the invention, during the initial phase of the continuous feed of material of the continuous pyrolysis process, the material is fed to the pyrolysis reactor Openable chamber cover at the feed end of the The advantage of the chamber cover is the accumulation of pyrolyzable material that can be moved by the screw conveyor, which can be kept open continuously after the initial phase and then has no further function, except during the reactor heating process, as long as the reactor is driven and the material is fed continuously.

According to a final and further developed design of the invention, a gas lighter than air or oxygen, preferably nitrogen, is fed in the upper part of said supply duct such that due to the mass ratio between the gases, all air and any free The oxygen is continuously pushed out from the supply pipe in the opposite direction to the conveying direction of the pyrolyzable material. Because of the inclined assembly of the supply pipe, the effect is that the supply pipe will operate in approximately the same way as a conventional water container, but with nitrogen instead.

Description of drawings

The invention will be described in more detail below on the basis of a preferred exemplary embodiment shown in the accompanying drawings, in which:

Figure 1 schematically shows a sectional view through the pyrolysis reactor from its side,

Figure 2 shows schematically the same reactor shown in Figure 1, but seen from above.

Detailed ways

Figure 1 schematically shows some devices, called pyrolysis reactors 100, for continuous operation. It should be noted that the entire reactor 100 is suitably arranged at an inclination angle of approximately 5 degrees to the horizontal. At the feed end of the reactor there is a feed hopper 1 in which material (eg segments of car tires) is fed downwards. At the bottom of the feed hopper 1 there is a feed screw arrangement 3 driven by a motor 2, which advances the segmented material at an inclination of 10 to 20 degrees. There is a pre-heating jacket 5 around the feed screw for heating the material to just above 100 degrees Celsius, thereby firstly allowing any moisture containing trapped oxygen to escape there and secondly softening the material so that it can be compacted more easily . At the upper end of the feed screw device 3 there are nozzles (not shown) for the supply of nitrogen, since nitrogen is lighter than both air and oxygen, which is satisfied due to the inclination of the device 3 so that it will expel any that is present at the feed hopper 1 air or oxygen. In addition to the above-mentioned nozzles for nitrogen, a further feed screw unit 6 driven by at least one motor 4 (using a double helix 7 driven in the same direction of rotation, but at a lower speed than the feed screw unit 3 ) is connected to the feed The upper end of screw device 3. One end 8 of the feed screw device 6 is arranged so that it is tightly sealed against the entry of ambient air into the reactor chamber 9 at a certain distance, at its end a chamber cover 10 is arranged, which can be in the closed position and in the open operate between locations. The function of the chamber cover 9 when starting the continuous pyrolysis process is to enable the establishment of an initial compact of process material from which all oxygen can be vented so that it can be driven outwardly by the feed screw arrangements 3 and 6 respectively to Feed bag. The feed screw arrangement 6 is followed by a reactor chamber 9 into which the briquettes fall to the bottom and out onto a slow moving conveyor belt 11 . Leveling plow blocks 12 are arranged in the initial part of the belt 11 so as to distribute the pressing material evenly on the belt 11 . During the continuous process, the pyrolyzed fragments are held in the chamber 9 for about 3 minutes, wherein the chamber is maintained in the hot zone 13 at a substantially constant temperature of about 550 degrees Celsius. In the top 14 of the thermal zone 13 there is a heating element 15, preferably an electric heating element of the infrared radiation type, since the heat supplied is of the radiative type, which is why the thermal zone 13 is protected at the respective ends of the thermal zone 13 by radiation protection means 16. Set boundaries. The radiation protection is mainly used to concentrate the heat discharge in the area in the hot zone 13 used for this purpose. After the passage through the zone 13, there is the remainder of the material for pyrolysis, which mainly consists of carbon black, which falls at the end of the conveyor belt to an intermediate storage (not shown) arranged for transfer to the sealed oxygen Conveyor screw 18 in outlet duct 17, this intermediate storage is emptied instantly if required.

A certain proportion of the material used for pyrolysis will inevitably work in an undesired manner and will fall beside the belt 11, or will be attached to it and will therefore possibly spontaneously fall at a later stage, while the material follows the belt 11 below the positioning. Depending on where this occurs, it happens that it is processed in the intended manner and falls out onto the pipe 17 as soot, or it falls under the belt 11 in the form of residual material. For this highly probable event, a further conveyor screw 18 is arranged at the bottom of the reactor chamber 9 which feeds this material and any liquid fraction to an outlet 19 arranged at the feed end of the reactor chamber 9 , the feed screw 20 feeds this material from the reactor chamber 9 into an oxygen-tight intermediate storage, which, like the above-mentioned intermediate storage, is emptied on the fly in case of need.

FIG. 2 shows the pyrolysis reactor 100 viewed from above rather than from its side as in FIG. 1 . Starting from the left, the motor 2 for the feed screw arrangement 3 is shown, followed by the feed bucket 1 and then the feed screw arrangement 3 surrounded by the preheating sleeve 5 . The device 3 is connected to a feed screw device 6 which in turn is connected at the outlet end of the device 6 to the reactor chamber 9 near the chamber cover 10 . Connected to the reactor chamber is firstly the gas outlet pipe 21 via which the gases released by the pyrolysis process are processed, secondly the outlet pipe 17 for carbon black etc. and thirdly for the remaining Outlet duct 19 for material and liquid portion. The pipes 17 and 19, as well as the pipe 21 have an intermediate storage function which requires occasional emptying. This of course happens without giving oxygen or air a chance, that is to say enter through the back door and distribute the process in the pyrolysis chamber.

Figure 3 schematically shows a device 22, which may be referred to as a liquid lock or scrubber, arranged in a tank or vessel 23, at the inlet of which gas from the reactor chamber 9 is pumped into In order to maintain an air pressure in the reactor chamber 9, which corresponds to the atmospheric pressure in the area around the pyrolysis reactor. The gas passes through conduit 24 down below the surface of the liquid so that it is released below the surface and allowed to diffuse to the collection means at P. The gas in question has a high calorific value and can be used in many different applications, such as fuel in gas-powered vehicles such as city buses. There is a discharge tap 25 at approximately half the height of the vessel 23 to enable any condensation product to form and to prevent the vessel 23 from filling beyond its width.

The pyrolysis reactor 100 arranged for continuous operation slopes downwards towards the feed end. The feed bucket 1 is sufficiently large that continuous operation can be maintained without any practical problems. The motor 2 is of such a type that its speed can be varied so that effective compression towards the double screw 7 can be guaranteed under all conditions, regardless of the type of material fed into it. For effective compression, and to ensure that all moisture is drained from the material used for pyrolysis, the material should reach a preheating temperature of 120 degrees Celsius in front of the chamber cover 10 of the hot zone 13 of the reactor chamber 9 . The chamber cover 10 is spring loaded into the open position, but is activated whenever an oxygen detector (not shown) arranged in the conveyor tube of the feed screw assembly 6 indicates that there is oxygen in the compressed or hot zone 13 of the tube. A lock (not shown) remains closed. The oxygen detector is also controlled by a computer and associated software suitable for the purpose whether to supply nitrogen. For example, if any one of the motors 2, 4 in the feed screw arrangement fails, all feed and heating elements 15 are switched off, as is the chamber cover 10 with active control means (not shown) arranged according to the intended use. Under these conditions, it is appropriate to maintain a nitrogen atmosphere in the feed screw tube and reactor chamber 9 until the temperature therein has dropped to such a level that there is no longer a risk of fire in the material used for pyrolysis. The temperature in the hot zone 13 (which is maintained by means of heating elements mounted on top of it) is controlled by thermostats and software in the computer so as to remain at approximately 550 degrees Celsius +/- 5 degrees Celsius, as it passes through the hot zone 13 The degassing of the material supplied and leveled by the plow blocks 12 is done as far as possible. The invention is not to be considered limited by this description of its preferred embodiments, but only by the appended claims.

Claims (11)

1. A method for the continuous operation of a pyrolysis reactor, whereby oxygen or any gas mixture containing oxygen, such as air, is excluded or prevented from flowing into the interior of the reactor containing A supply conduit for the material to be pyrolyzed, means for transporting the material through said supply conduit, a pyrolysis reactor with the means necessary for pyrolysis isolation, means for removing gases released during the pyrolysis process and A mechanism for removing residual product, for example residues, characterized in that the material in the feed duct is conveyed by a first screw towards an inclined portion in the duct and towards at least one of the feed ducts A further second screw conveyor feeds, said feed conduit being connected to said supply conduit, wherein the second conveyor is driven at a lower speed than the first conveyor. 2. The method according to claim 1, characterized in that the material for pyrolysis is fed by a first screw conveyor towards a unit comprising two screw conveyors rotating in the same direction. 3. A method according to claim 2, characterized in that respective screws in a unit comprising two screw conveyors are driven at different speeds. 4. A method as claimed in claim 3, characterized in that the screw conveyor with the highest speed in said unit with two such conveyors is also driven at a speed lower than the speed of said first screw conveyor . 5. The method according to any one of the preceding claims, characterized in that at the beginning of the continuous feeding of the material of the continuous pyrolysis process, said material is directed towards the feed end of the pyrolysis reactor. Chamber cover feed. 6. A method as claimed in any one of the preceding claims, characterized in that a gas lighter than air or oxygen, preferably nitrogen, is fed in the upper part of the supply duct such that due to the mass between the gases Than, all air and oxygen are continuously pushed out from the supply duct. 7. A device for the continuous operation of a pyrolysis reactor, the purpose of which is to prevent the spontaneous flow of oxygen-containing gas, preferably air, from the outside into the interior of said reactor containing A supply conduit for the material, means for transporting this material through said supply conduit, a pyrolysis reactor with the means necessary for pyrolysis isolation, means for removing gases released during the pyrolysis process and for removing Mechanism for residual products, such as residues, characterized in that said means for continuously operating a pyrolysis reactor comprises a feed hopper, a driven first screw arranged at the lower end of said feed hopper a conveyor, which can rotate at a certain speed in a conveyor duct with a slight upward slope designed for said conveyor, a screw conveyor arranged at the end of said first screw conveyor and its duct, which In the feed conduit to said pyrolysis reactor, said means for continuously operating a pyrolysis reactor itself comprises at least one screw conveyor driven at a lower speed than said first screw conveyor. 8. The apparatus of claim 7, further comprising a chamber cover operable to open and close from the interior end of the supply conduit from the exterior of the pyrolysis reactor toward the chamber The pyrolysis material of the cover is designed to be encapsulated during the start-up process of the continuous operation cycle of the pyrolysis reactor. 9. Apparatus according to any one of claims 7 or 8, characterized in that it comprises a preheating zone along the transfer conduit designed to dry and soften the material for pyrolysis. 10. The device according to claim 9, characterized in that it comprises an oxygen detector arranged firstly in the reactor part, and secondly such a detector arranged in a supply conduit connected to said reactor, said The detector is connected to a control system through which, if the presence of air or oxygen is detected, the oxygen of the exhaust gas is fed in the upper part of the supply pipe so that due to the mass ratio between the gases, all the air and oxygen are continuously pushed out from the supply pipe. 11. The apparatus of claim 10, wherein the control system is connected to a sensor that detects whether the screw conveyor is rotating, wherein the The control system described above ensures that the reactor chamber is closed downwards and an atmosphere comprising mainly nitrogen is maintained in the conveyor and reactor chamber.

Images