WO2009081434A2

WO2009081434A2 - Process and apparatus for the disposal of refuse containing metals, inert and organic fractions

Info

Publication number: WO2009081434A2
Application number: PCT/IT2008/000628
Authority: WO
Inventors: Enzo Ranchetti
Original assignee: Enzo Ranchetti
Priority date: 2007-12-21
Filing date: 2008-10-03
Publication date: 2009-07-02
Also published as: WO2009081434A3; EP2231836A2; ITBS20070210A1; RU2010129901A

Abstract

The invention concerns a process and an apparatus for the heat treatment and disposal of refuse containing at least an organic fraction and inert materials and metal, in particular but not only, scrap known as 'car-fluff'. The starting material is loaded into at least one closed and heated primary reactor in which the organic fraction in the material undergoes molecular disassociation by heating up to a temperature of 450-4800C to transform it into combustible gas and steam with the formation, without oxidation, of solid residue/ashes containing inert materials and metals. Then, on one hand, the gas and steam generated in this way are used as a combustible source at least for the production of thermal energy to be used for heating the primary reactors and, on the other hand, the residue/ashes are collected to select and recover at least the metals they contain.

Description

"PROCESS AND APPARATUS FOR THE DISPOSAL OF REFUSE CONTAINING METALS, INERT AND ORGANIC FRACTIONS"

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Field of the Invention

This invention relates to the disposal and exploitation of refuse, in particular but not limited to materials such as: organic and non organic compost; compounds from the scrapping of automobiles, mass also known under the name of "car-fluff¹; white goods, electric and electronic equipment and the like; solid urban waste (SUW) coming from non differentiated deposits; in general any refuse containing both organic components and metal and/or inert components. State of the Technique Car-fluff is a material that remains following the milling and selection of car carcasses; operations aimed at extracting ferrous and non-ferrous metals comparable to waste from initial mass to be re-used in the metallurgical sector.

It represents a considerable percentage (about 27%) of the total weight of a car and contains, together with fractions of ferrous and non- ferrous metals which cannot be extracted using conventional methods, a variety of mixed materials such as: rubber, glass, wood, cables, plastic materials, synthetic and non - synthetic fabrics, grease, lubrication oils, paints, fuel, plaques, earth, oxides, etc. The non organic fraction of this complex material can be calculated as being about 25% in weight and at least 20% of this fraction is represented by non ferrous materials such as: copper, aluminium, zinc, lead, brass and the like. Disposal in dumps of this material, besides not being allowed because it has been classified as dangerous rubbish; it would however be costly besides being a great waste.

This led to the convenience and the idea, then transformed into a project, to salvage as best as possible, the materials contained in the "car- fluff' such as: the organic products to produce energy and the metals to be recycled.

At the moment, processes and plants for treatment both for the incineration and gasification of waste materials, which however applies mainly to only solid urban waste or comparable to rubber or used plastic, are well known. Likewise, incinerators of various types, with a movable grid, rotating drum, liquid fluid and others still, whereby however the process is carried out at relatively high temperatures and with air feed, and consequently with the risk of provoking damaging oxidation processes and cause, where present, at least the fusion of some metals. Efficient processes for treating, conditioning and recovering some materials deriving from scrapping and to generate, at the same time, useable energy without causing the fusion of metal fractions and the emission of harmful substances, do not seem to be available.

Also the process described in document US-6938562, which also regards pyrolytic treatment of waste, besides being discontinuous, does not seem suitable for treatment of car-fluff or other materials from scrapping and does not envisage either the selective aspect and recycling of some residual materials, or the co-generative aspect of energy, not contemplating even self-feeding of the system, so much so that it requires a high energy external source.

Objective and Summary of the Invention

The objective of this invention is instead to create the conditions for an effective disposal of waste, including the so-called car-fluff, with a profitable recovery of ferrous and non ferrous metals contained in it, basically cleaned again, and a simultaneous production of combustible gas able to feed a system for thermal and electric co-management, above all substantially without producing polluting substances.

Such an objective is reached by means of a heat process that consists in: • loading the starting material into at least one closed and heated primary reactor;

• a molecular disassociation carried out by heating of the mass of material to be treated in a primary reactor in an anaerobic condition (similar to pyrolysis but at a very low temperature) up • transforming into gas and steam of all the organic fractions of the starting material and a production, without oxidation, of residue/ashes containing inert metal materials, substantially a distillation followed by cracking;

• canalizing and using the gasses and vapours, generated in this way, as fuel for the production of thermal energy, • recovering inert materials and metals from the ashes followed by a selection process.

Advantageously, the gasses or steam (also called Sin gas) can be used in part for self-consumption by the reactor and system and the rest to feed a boiler for at least the production of hot steam and/or hot water and, where envisaged, the steam can be used to feed a turbine for the production of electric energy and at the same time hot water for heating and/or conditioning (by means of the latest absorbers).

The objective of the invention is likewise achieved with an apparatus for the heat treatment of scrap, including an organic fraction and inert materials and metals, that basically comprise; at least one primary reactor provided to receive the starting scrap, closed hermetically, operating in the absence of oxygen, heated externally up to the required temperature, not higher, to prime internally the molecular dissociation of the organic fractions with consequent production of gas and steam, leaving intact, not melted and not oxidized, residue/ashes containing inert materials and metals; means for transporting the gasses and steam exiting said primary reactor to a secondary reactor for their combustion and production of at least thermal energy; means for unloading, selecting and recovering the inert materials and metals from the primary reactor.

In particular the secondary reactor can be made up of a boiler at least for the production of steam and/or hot water connected to means to use the thermic content of the steam and/or the hot water. Detailed Description of the Invention

The invention will in addition be described in detail in the continuation of the treatment which refers to the enclosed drawing, in which the only figure shows a schematic view of the apparatus designed in particular for treatment and disposal of car-fluff.

As shown, this apparatus comprises one or more primary reactors 11 , one secondary reactor 12, a system for the production of electric energy 13 and at least one heat exchanger 14 to recover the thermic content of the fumes before they are discharged into the atmosphere through the stack 15. Each primary reactor 11 can be associated with a load container 16 complete with a weighing system, provided to receive the start material and convey it under control into reactor itself by means of a conveyor 17 and a feed system which tends to keep out the air. Preferably the conveyor 17 is set up to collect the material from the bottom of the container; therefore it is the material deposited first that is collected thus avoiding dangerous stagnation.

Although not shown, each primary reactor 11 is provided with a heating system, preferably the induction type, for heat treatment of the loaded material until the formation of gas or steam and ashes, that is to say residual solids.

Each primary reactor 11 can therefore be basically in the shape of an induction furnace, connected at the top to the secondary reactor 12 by means of insulated canalizing 18 with Sin gas flowing through it which generates following heat treatment. In the bottom area, each primary reactor has a sealed outlet 19, to discharge the residue/ashes, which tends to exclude the entry of air, and which connects up to a container 20, fed by a hermetic transport system, acting also as a heat disperser, tending to exclude and/or limit the entrance of air, to collect inert residue and metals not blackened by oxidation. Each primary reactor will furthermore be equipped with means of control to manage the heating process of the starting mass correctly and in safety.

The secondary reactor 12 is represented by a boiler for the production of high pressure steam designed to feed the system for the production of electric energy 13 that will include a turbine 21 , associated with an electric generator 22, the output of which is connected to a condenser 23.

The heat exchanger 14 will be provided in connection to the secondary reactor 12 and the stack 13 with the interposition of a fan 24 for the controlled circulation of the aeriforms, of a dry scrubber for fumes 25 and a bag filter 26.

According to the treatment process proposed, the start material will be loaded into each primary reactor, which will be closed and already heated to a maximum temperature of 450-480⁰C, substantially oxygen absent and for a prolonged period of time of 6- 10 hours, and in any case sufficient to cause molecular disassociation of all the organic fraction present in the treated material, as in a batch or pseudocontiniuos process.

It is of great importance to reach and maintain a certain temperature, without exceeding it, as long as disassociation from any biological and organic complex such as : wood, plastic, rubber, fabrics, oil, etc has been proved to be sufficient, but not able to reach fusion point, and even more so, to sublime, any metal.

At that temperature the starting material is treated and generates combustible gas and steam from the organic fraction, including ashes, that is solid residue, containing various inert materials and metals. Given also the substantial absence of oxygen, there are no uncontrollable oxidative reactions which in general are the prime cause of the formation of highly toxic compost; the same applies to the traditional flame furnaces assigned for combustion/incineration of solid urban waste (SUW) with a high content both of organic and inert materials and metals. Therefore, with the process proposed herein avoids the formation of toxic substances such as: dioxins, furans, aldehydes, ketones, pm 10, and even the fearful and extremely dangerous, Nan particles, often reported and the cause for further pollution and damage to the environment.

The treatment of starting materials during their long permanence in every primary reactor will feed a variable but continuous flow of gas and dense steam, all devoid of unwanted composts and/or metal oxides, but highly energetic and combustible, because they are only made up of organic substances and, in the initial stage, also of water.

Water, certainly present in all refuse to be treated, will not have any influence over the combustion process of the gasses as its percentage is very low and it rapidly evaporates.

The combustible gasses exiting each primary reactor are transported hot and injected, together with an appropriate quantity of combustive air, into the secondary reactor, boiler or adiabatic chamber, for the production of high pressure steam. The combustive air may be preventively heated, about the same temperature of the gasses, by means of heat exchanger interacting with the combustion fumes of the boiler 14 it will be coupled to, so as to optimize the combustion process and in addition, achieve a recovery of the heat content of the fumes before they are sent to the stack 15 through the dry purifier 25 and the bag filter 26.

The high pressure steam obtained in the boiler can be canalized and used to feed a steam turbine 21 and to operate, through this, a generator 22 for the production of electric energy. The exhausted steam in exit from the turbine will then pass through a condensator 23 for condensing so as to close the water circuit to be recycled in the system.

Moreover, and advantageously, a part of the steam in exit from the condensator may be tapped for heat exchange with a fluid circulating in heating or district heating systems.

The combustible gasses in exit from each primary reactor may also be used in a boiler to heat diathermic oil placed in circulation to contribute to the heating of the primary reactors.

For example, in fact, in the case where at least three reactors are used, the process foresees heating two with diathermic oil up to a maximum of the capacity (320-330⁰C) achieving a complete distillation reaction of the organic fractions. The residual material of the third reactor will be transferred, heated using heating elements to a temperature of about 48O⁰C, to complete the molecular disassociation process and consequently the cracking process. In this reactor, which can be smaller in size compared with the others, will also take place in the final phase, which is the finishing of the process, the cracking of the carbonaceous fractions by blowing air through it for partial controlled oxidizing as described below.

As regards to the system, the secondary reactor or boiler 12, can be equipped, in the combustion chamber and close to the tube nest, a modern transparent ceramic material (silicon carbide - Porous Ceramic) heat exchanger and an open cell micro, capable of acting as a catalyst for the reforming of many substances and able to maintain the incandescent combustion steam at a high temperature for a lengthy period of time(considerable increase in stay time) favouring in this way complete oxidation and further improvement of the quality of the fumes discharged from the stack.

In essence, in the disposal process proposed herein, only the gas and steam will be burnt, therefore only aeriforms, which will come from the organic fractions of the starting material treated in each primary reactor, without any presence of heterogeneous solids.

Their combustion will be simple and complete, and thanks to the increase in stay time in the boiler, the discharge of the combustion will be much lower than the severest of parameters in force and by no means polluting.

On the other hand, the residue or ashes deriving from the heat treatment in each primary reactor will only contain inert loads (typical residue of the thermoplastics or the like), clean glass, earth and plaques and, mainly, non fused and non oxidized metals, perfectly cleaned and, as such, recyclable with a very high market value, after being separated and selected. In some cases, however, during low temperature molecular disassociation formation of carbonaceous groups or pyrolysis coke was experienced, above all when the starting material contained a high quantity of products with vegetable origin such as: paper, wood, branches, dried fruit and all kinds of seeds.

This material is classified as a non harmful residue, on the contrary it can have a market value, even though low, but sufficient to justify being selected and recycled. However its disposal in a reactor, due to a formation of coke in the ashes that may reach important percentages, even over 20%, with a caloric content of about Kcal. 2.500/Kg.

As said before, where required, it is possible to also eliminate the pyrolysis coke obtaining thermal energy from it already in the primary reactor, which will then flow into the secondary reactor increasing its yield. It is then necessary to insufflate natural air on the bottom of the primary reactor, when the molecular disassociation is nearing termination and the production of Sin gas is at a minimum, distributing it using very small nozzles so as to oxidize the ashes as best as possible.

The total percentage of exchange oxygen must not exceed 6%. It has been observed and proved that in about one hour, just at the end of the process, this buffered and partial oxidation is sufficient to eliminate the presence of the coke and all the soot formations possibly present in the reactor.

This treatment does not alter the maximum temperature foreseen in the process. In fact, if the oxidation, even if partial, increases the temperature, the successive evaporation and release of the newly formed carbon dioxide (CO2) (latent evaporation heat) tends to lower it, restoring in this way the primary ambient of the reactor. All taking place, moreover without in any way invalidating the quality of the metals to be recovered because no notable oxidation takes place, but only in the case of the coke which is more reactive and has a more substantial mass.

Furthermore, treatment of this kind of the pyrolysis coke does not alter the energetic balance, if anything positively, of the complete process; on the contrary it intervenes by varying the composition of the fumes which will have, although minimum, a higher carbon dioxide (CO2) content, absolutely justifiable and legal however, it being pyrolysis of vegetable products.

In this way, the components of the ashes, not very exploitable and/or not recyclable, will be a very small quantities and may be disposed of in dumps without any risk of pollution or delivered to users of inert selected material (such as, for example, asphalters, mortar producers, etc.). From the process and system described above, besides an efficient disposal of materials such as scrap or car-fluff, otherwise impossible without facing environment and pollution, important economic benefits will be gained deriving both from the production of electric energy which will be available in excess of the amount auto-consumed and necessary to make the system function and from the production and availability of thermal energy for various uses, both from the recovery of recyclable metals and the good market value.

Claims

"PROCESS AND APPARATUS FOR THE DISPOSAL OF REFUSE CONTAINING METALS, INERT AND ORGANIC FRACTIONS"* * * * *C L A I M S

1. Process for the heat treatment and disposal of refuse in general containing at least an organic fraction and, together, refuse also containing inert materials and metals, in particular but not only, scrap named "car-fluff" comprising the steps : • loading the starting material into at least one closed and heated primary reactor;

• causing molecular disasspciation of all the organic fraction of the starting material by heating until it is transformed into combustible gas and steam and a formation without oxidization of the solid refuse/ashes containing inert and metal materials;

• using, on the one hand, the gas and steam generated as a combustible source at least for the production of thermal energy to be used for the heating of each primary reactor;

• collecting, on the other hand, the residue/ashes for selection and to recover at least the metal it contains.

2. Process according to claim 1 , characterized in that the starting material, in each primary reactor, is heated up to a temperature not exceeding 450-480⁰C and for a prolonged time of between 6-10 hours, sufficient for the complete molecular disassociation of the organic fraction.

3. Process according to claims 1 and 2, characterized in that the heating of the starting material in each reactor is carried out basically in the absence of oxygen to avoid oxidative reaction.

4. Process according to the previous claims, characterized by the blowing of natural air by means of very small nozzles onto the residue/ashes on the bottom of each primary reactor so as to oxidize the carbonoise groups or pyrolysis coke when the molecular disassociation is terminating and the production of gas and steam is diminishing.

5. Process according to the previous claims, in that at least a part of the gasses or steam generated are fed to a boiler for the production of steam and/or hot water, the steam being able to be used to feed a turbine for the production of electric energy and the hot water system for heating or conditioning systems.

6. Process according to any of claims 1-4, characterized in that at least a part of the gas or steam generated is fed to a boiler to heat diathermic oil used to heat at least one or more primary reactors.

7. Apparatus for the heat treatment and disposal of material containing at least an organic fraction together with inert material and metals, in particular, but not only, scrap also named "car-fluff, characterized by at least one primary reactor designed to receive the starting materials, closed and heated externally until it causes a production of gas and steam by the organic fraction present in said scrap and the formation, on the bottom of the reactor and without oxidation, of residue/ashes containing inert materials and metals, means for delivering the gas and steam exiting said primary reactor to a secondary reactor for their combustion and the production of at least thermal energy and means for downloading the residue/ashes from each reactor followed by the recovery of the metal they contain.

8. Apparatus according to claim 7, wherein each primary reactor comprises an induction boiler and heated to a temperature not higher than between 450-480⁰C and without oxygen.

9. Apparatus according to claims 7 and 8, wherein each primary reactor is associated with a container to receive the starting material and to send the latter to said reactor, said container having means for collecting the material always from the bottom.

10. Apparatus according to claims 7 to 9, wherein the secondary reactor is made up of a boiler for the production of steam and/or diathermic oil, fed by gas and steam provided by each primary reactor together with comburent air, and where the steam is canalized to feed a turbine powered by an electric energy generator, and the heated diathermic oil is used to heat at least some of the primary reactors.