Pyrolytic method and apparatus

Abstract

A method and an apparatus for pyrolytically decomposing carboniferous materials provided with a reactor connected by a carbonization gas conduit to a multiple stage condenser for fractionally recovering pyrolysis oils in a collection container, a central heating element connected to an external heat source, a pre-heating chamber for receiving material after pyrolysis and material prior to pyrolysis for an exchange of heat therebetween, first conveying means for alternatingly moving non-pyrolyzed and pyrolyzed material from the pre-heating chamber into an out of the reactor and second conveying means for moving non-pyrolyzed and pyrolyzed material out of and into the pre-heating chamber. For moving and pyrolyzing the material is preferably retained in basket-like receptacles. The condenser may be connected to the external heat source for utilizing residual carbonization as supplemental heat energy. To render the apparatus moveable, the reactor gas conduit and condenser, the pyrolysis oil collection container, the first and the second conveying means are mounted in separate but connectable container modules.

Description

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a novel method and an apparatus for pyrolytically decomposing materials and mixtures of materials of, in particular, solid carbon compounds such as plastics, rubber and materials and mixtures of materials contaminated by solid or liquid toxic or noxious substances.

[0003] 2. The Prior Art

[0004] Processes and apparatus of an industrial kind are known for thermally decomposing plastics and rubbers. The materials are initially fed into a closed container, also known as a reactor, and the reactor is then heated from the exterior in the manner reminiscent of an oven. Temperature and dwell or reaction time are selected or determined as a function of the kind of material to be decomposed.

[0005] The pyrolytic reaction is carried out under the effect either of pressurized air as disclosed, for instance, by German patent specification DE 42 43 063 C2 or without pressure as disclosed, for instance, by German patent specifications DE 102 19 440 A1, DE 29 49 983 A1, DE 103 09 530 A1.

[0006] The known methods and apparatus share the disadvantage of requiring heating of the reactor containers from the exterior, by way of, or through, their shell. The particular drawback in connection with a pyrolytic process utilizing such reactor containers is that heat penetration takes place but slowly, particularly in the case of large diameter reactors, and that the distribution of heat within the reactor is substantially irregular or non-uniform. This at best mitigates against an optimized process control and practically renders impossible any kind of economic or efficient use of energy.

[0007] The reaction products are solids, usually carboniferous granular products containing admixtures of other substances, carbonization gases and mixtures of so-called pyrolysis oils condensed from the gases.

[0008] Such pyrolytic processes and apparatus are also unsuitable for thermally recovering contaminated materials and mixtures thereof, such as, for instance, soil contaminated by industrial plants, construction sites or road traffic, or by accidents.

[0009] The known pyrolytic processes are practiced in stationary apparatus which, of course, requires transportation of the material to be pyrolyzed to the pyrolysis plant.

OBJECTS OF THE INVENTION

[0010] It is an object of the invention to provide a pyrolytic method and compact apparatus for practicing the method which makes possible an improved and effective endothermal use of the energy for generating the heat required for the process.

[0011] Another object is to provide a pyrolytic apparatus which is mobile and may, therefore, be used where it is needed.

[0012] Furthermore, it is an object of the invention to provide an apparatus of the kind referred to which allows in situ processing of liquid pyrolysis products to various fractions.

BRIEF SUMMARY OF THE INVENTION

[0013] In the accomplishment of these and other objects, the invention provides for a pyrolytic method in which the pyrolysis material is filled into a receptacle of basket-like structure, placing the receptacle and its contents into a heated chamber for pre-heating, moving the pyrolysis material into the pyrolysis reactor, creating slight vacuum pressure in the reactor during a reaction time depending upon the kind of pyrolysis material to remove carbonization gases from the reactor, heating the carbonization gases in an after-heater, fractionally removing pyrolysis oils from the gases by condensation, feeding the condensates to collection containers and feeding the gases to a heat generator for heating the pyrolysis reactor, controlling the reaction temperature and the temperature of the after-heaters and the condensers as a function of the pyrolysis material and of the temperature of the carbonization gases, the thermal control of the pyrolytic process being carried out as a ratio control of the temperatures of the heating element, the interior of the reactor, the carbonization gas, the after-heater and condenser, terminating the carbonization process in response to a signal from a sensor in the condenser, introducing an inert gas or a mixture of inert gases into the reactor and into the condensation chamber for purging the carbonization gas containing areas of the pyrolysis apparatus, removing the heated receptacles and any solid pyrolysis product contained therein from the reactor and placing them into the pre-heating chamber for pre-heating, by heat-exchange, further receptacles filled with fresh pyrolysis material contained therein and, once an exchange of heat has taken place after a predetermined dwell-time, removing the receptacles and pyrolytic products contained therein from the pre-heating chamber, emptying the receptacles and returning them to the pyrolytic process loop.

[0014] In accordance with a preferred embodiment of the invention, the apparatus for practicing the pyrolytic method consists of main component groups including a heat generator, the pyrolysis material receptacles, a feeding device, at least one pre-heating chamber, a pyrolysis reactor, a carbonization gas conduit, a blower, at least one carbonization gas after-heater, a distillation column or condenser, a process control and regulating device as well as an inert gas purging device, charge, discharge and conveyor devices for pyrolysis materials, pyrolysis products and condensates.

[0015] Preferably, the structural groups are arranged in either a closed or a frame-like container or in more than one connectable modular closed or frame-like containers. They may be variably grouped in horizontal and/or vertical arrangements. For charging and discharging, the pyrolyses reactor is provided with a bottom plate for selectively opening and closing the reactor. To this end, either the bottom plate or the bonnet-like upper portion of the reactor may be vertically movable for respectively charging and discharging the receptacles containing the pyrolyses material or products. The basket-like structure of the receptacles is such that their sidewall is permeable by heat and that their bottom prevents escape of either the pyrolyses material or product.

[0016] The reactor is provided with at least one centrally disposed heating element or with additional heating elements within the reactor and in the side surfaces thereof. In order to prevent back-flow of the condensed carbonization gases to the reactor or to prevent the gas conduit from becoming congested, the carbonization gases are conducted and after-heated in a manner that provides for their condensation at fraction stages provided for it.

[0017] Since the apparatus is housed within a container or within a plurality of connectable container modules such as, for instance, a reactor module, heater module, fuel-tank module, condenser module, charging module for the pyrolyses material and/or unloading module for the pyrolyses product, the method and apparatus in accordance with the invention are mobile and thus suitable for use at any site where they may be needed.

[0018] The energy efficiency is significantly improved as a result of the process sequence as well as the structure of the reactor including its centrally arranged heating element and the conductance and inclusion of the carbonization gases as well as, optionally, low-value condensates into the heating system.

DESCRIPTION OF THE SEVERAL DRAWINGS

[0019] The novel features which are considered to be characteristic of the invention are set forth with particularity in the appended claims. The invention itself, however, in respect of its structure, construction and lay-out as well as manufacturing techniques, together with other objects and advantages thereof, will be best understood from the following description of preferred embodiments when read in connection with the appended drawings, in which:

[0020] FIG. 1 is a view in longitudinal section of a pyrolysis reactor module and a condenser column;

[0021] FIG. 2 is a view in longitudinal section of a pyrolysis material receptacle including a conveyor and lifting device;

[0022] FIG. 3 depicts a pre-heating chamber charged with pyrolysis material receptacles in longitudinal section;

[0023] FIG. 4 is a view in longitudinal section of a pyrolysis reactor module with closed bottom and centrally disposed heating element, carbonization gas conduit, condenser for fractioning distillation, after-heater and blower;

[0024] FIG. 5 depict a condensate collection container; and

[0025] FIG. 6 is a schematic block diagram of the modular container structure of the pyrolysis apparatus including charging and discharging devices as well a pre-heating chamber.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0026] The initial step in carrying out a pyrolytic process in accordance with the invention is the filling of receptacles 13 with material to be pyrolyzed such as, for instance, oil contaminated soil. The receptacles have a capacity of about 300 liters. The filled receptacles 13 are moved by appropriate conveying means, such as carriages 15, to a pre-heating chamber 17 where they will stay for the duration of a pyrolytic reaction cycle for the purpose of warming up by heat exchange with previously pyrolyzed material in receptacles 13 removed from a reactor 1. Thereafter, they are moved into the reactor 1 through an opening formed by removal of a bottom plate 9 of the reactor 1 and placed around a central heating element 2, which preferably is a radiation heater. The source of heat (not shown) for the heating element 2 is an external one and may be electric, oil or gas fired, including by gas recovered from the pyrolytic process in accordance with the invention. As shown in FIGS. 2 and 3, the bottom plate 9 serves as a support for the charged receptacles 13. Removal of the reactor bottom plate 9 for loading the receptacles is accomplished by vertical relative movement between the bottom plate 9 and the reactor shell. Preferably, the outer or lower surface of the bottom plate 9 or the load surface of the carriage 15 is provided with an appropriate hoisting apparatus 16 schematically indicated in FIG. 2. After closure of the reactor 1, the pyrolytic process proper is commenced by raising the operating temperature within the reactor chamber to about 500.degree. C. Any carbonization gases developing during the pyrolytic reaction cycle are fed by a blower 5 through a conduit 3 and an after-heater 4 across coolers 6 of a condenser column or distillation device 7 for the fractional precipitation of the condensate into different cavities connected by conduits 10, 11, and 12 to different compartments of a collection container 18 (see FIG. 5). As shown in FIG. 2 by way of example, the condenser column 7 consists of three stages. After passing the condenser column 7, the gases are fed by way of appropriate channels (not shown) as a supplemental source of energy, to the heat generator for heating the reactor 1. It will be understood by skilled artisans that the reactor 1 and the gas conduit 3 and appurtenant distillation stages 7 are insulated to prevent heat from escaping from or penetrating into them.

[0027] The pyrolytic process cycle usually terminates after about 100 minutes and is followed by purging the carbonization gas conducting units, such as conduit, channels and chambers with an inert gas such as, for instance, nitrogen. Thereafter, the bottom plate 9 of the reactor 1 is opened for removal of the receptacles 13 containing pyrolyzed products, such as carbonization coke and soil substances, by the carriage 15 for positioning in the pre-heating chamber 17. Here, the receptacles 13 and their contents are cooled by heat exchange with other receptacles 13 filled with new material to be pyrolyzed. Thereafter, the pyrolysis products are discharged from their receptacles 13 which may then be returned into the process loop to be charged with fresh material to by pyrolyzed.

[0028] The apparatus for practicing the pyrolytic process consists of such major structural component groups as a heat generator, pyrolysis material receptacles 13, a conveyor device or carriages 15, a pre-heating chamber 17, a pyrolysis reactor 1 including a conduit 3 for carbonization gases, a blower 5, a carbonization gas after-heater 4, a condenser or distillation column 7, a process control and regulating device (not shown), an inert gas purging device including a container 8 for inert gas and, last but not least, charging and discharging devices for pyrolysis materials and substances 14, such as coke, coke mixed with other solids, and the condensates.

[0029] By way of example, the component groups consisting of the pyrolysis reactor 1 including the carbonization gas conduit 3, the blower 5, the carbonization gas after-heater 4, the condenser or distillation column 7, the process control and regulating device as well as the inert gas purging device may be arranged within a container module 20 which may, for instance, be a frame structure.

[0030] The condensate collection container 18 including an equalizing container 19 may be mounted in a container module 21.

[0031] The pre-heating chamber 17 for providing heat exchange between "new" receptacles 13, i.e. the ones containing material to be pyrolyzed, and "used" receptacles 13, i.e. those removed from the reactor 1 and containing pyrolyzed substances, and the hoisting device 16 for charging and discharging the reactor 1 are mounted in a container module 22.

[0032] A further container module 23 of frame-like structure is provided to accommodate a charging unit for the pyrolysis material 14 as well as a discharging unit for the residual pyrolysis coke mixture and pyrolyzed soil substances.

[0033] The reactor module 20 is preferably placed over the pre-heating chamber module 22. The condensate collection container module 21 is placed over the charging and discharging module 23. The pyrolytic reactor 1 is provided with a bottom plate 9 which can be selectively opened and closed for respectively charging and discharging the reactor 1 from and into the lower pre-heating chamber module 22 by means of the hoisting device 16. Preferably, it is the bottom plate 9 rather than the reactor shell which is moved. It will, however, be understood by those skilled in the art that as an alternative the shell of the reactor 1 could be lifted off the bottom plate 9. The receptacles 13 for the pyrolysis material are of a basket-like structure having a bottom preventing the contents of the receptacle 13 from escaping and a side wall easily penetrated by heat from the heating element 2 which is preferably disposed in the center of the reactor 1 so that a plurality of receptacles 13 may be placed around it.

Claims

1. A method of pyrolyzing in a heated reactor material containing at least one of carbon and other pollutant, comprising the steps of: a) placing at least one first charge of material for pyrolyzing into the reactor for a predetermined time; b) preparing at least one second charge of material to be pyrolyzed; c) providing a pre-heating chamber; d) placing the pyrolyzed at least one first charge into the pre-heating chamber upon termination of the predetermined time; e) placing the at least one second charge into the pre-heating chamber for pre-heating by heat exchange with the pyrolyzed at least one first charge; f) placing at least one third charge of material for pyrolyzing into the reactor for said predetermined time; g) preparing at least one fourth charge of material to be pyrolyzed; h) removing the pyrolyzed at least one first charge from the pre-heating chamber; i) moving the pyrolyzed at least third charge from the reactor into the pre-heating chamber; j) placing the at least second charge of material for pyrolyzing into the reactor for the predetermined time; k) placing the at least fourth charge of material into the pre-heating chamber for pre-heating by heat exchange with the pyrolyzed at least one third charge; and l) thereafter sequentially removing pyrolyzed charges from the pre-heating chamber for replacement by pyrolyzed charges from the oven and moving pre-heated charges from the pre-heating chamber to the reactor for replacement by charges of material to be pyrolyzed.

2. The method of claim 1, wherein the at least one charge is placed into at least one receptacle of basket-like structure.

3. The method of claim 2, wherein the reactor is heated by a heating element centrally positioned therein and wherein the receptacle is positioned adjacent to the heating element.

4. The method of claim 1, wherein the temperature is about 500.degree. C.

5. The method of claim 1, wherein the predetermined time is about 100 minutes.

6. The method of claim 1, further comprising the steps of: moving carbonization gases developed by the pyrolysis through a duct and over condensing means for fractionally precipitating liquids contained in the gas.

7. The method of claim 6, wherein the carbonization gases are moved by a blower.

8. The method of claim 6, further including the step of moving the carbonizing gas through an after-heater.

9. The method of claim 6, further including the step of purging carbonizing gases by an inert gas.

10. The method of claim 9, wherein the purging is carried out with nitrogen.

11. The method of claim 6, further including the step of feeding at least some of the carbonization gas to the heating element for combustion thereby.

12. An apparatus for the pyrolytic decomposition of carboniferous materials, comprising: a reactor comprising a housing shell and a bottom plate mounted thereon for selective movement between open and closed positions; a heating element centrally disposed within the reactor and heated from an external heat source; a condenser comprising a plurality of stages for fractionally condensing pyrolysis oil; a gas conduit means for feeding carbonization gases from the reactor to the condenser; means connectable to the condenser for collecting pyrolysis oil; at least first and second receptacles for receiving carboniferous material for pyrolyzing; a pre-heating chamber for receiving one of the first and second receptacles after pyrolyzing and the other of the first and second receptacles prior to pyrolyzing; first conveying means for alternatingly moving the first and second receptacles between the pre-heating chamber and the reactor; hoisting means for alternatingly raising and lowering the first and second receptacles into and out of the reactor; and second conveying means for alternatingly moving the first and second receptacles into and out of the pre-heating chamber prior to and after pyrolyzing.

13. The apparatus of claim 12, further comprising a blower for feeding carbonization gases from the reactor to the condenser.

14. The apparatus of claim 12, further comprising means for purging the reactor, gas conduit and condenser from carbonization gas.

15. The apparatus of claim 14, wherein the purging means comprises a source of inert gas.

16. The apparatus of claim 12, wherein the means for collecting pyrolysis oil comprises an equalizing container.

17. The apparatus of claim 12, wherein the reactor, gas conduit and condenser, the first conveying means and the hoisting means, the pyrolysis oil collection means, and the second conveying means are mounted in separate container modules.

18. The apparatus of claim 12, further comprising means for feeding carbonization gases from the condenser to the external heat source.