WO2004044492A1

WO2004044492A1 - Method and device for integrated plasma-melt treatment of wastes

Info

Publication number: WO2004044492A1
Application number: PCT/EP2002/012768
Authority: WO
Inventors: Ricardo Blach Vizoso
Original assignee: David Systems Technology, S.L.
Priority date: 2002-11-14
Filing date: 2002-11-14
Publication date: 2004-05-27
Also published as: AU2002358010A1

Abstract

A method for plasma-melt treatment of solid wastes and resources recovery includes the heating of slag/metal by plasma, charging wastes into a reactor-gasificator, running a multi-step gasification, supplying an oxygen-containing gas into the pyrolysis and gasification zone and releasing the resulting syn-gas, molten metal and slag from the reactor for subsequent processing. According to the method, preliminary briquetted wastes are forcedly supplied below the molten slag/metal interface via a cooled channel, plasma jets are generated by electrodeless plasmatrons and the oxygen-containing gas is supplied horizontally below the molten slag/metal interface. The associated device for carrying-out the method is also disclosed.

Description

METHOD AND DEVICE FOR INTEGRATED PLASMA-MELT TREATMENT OF

WASTES

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention generally relates to the processes and apparatuses for high-temperature conversion of the solid wastes into environmentaliy neutral commercial products and for resources recovery. More particularly, invention relates to the integrated systems "plasma reactor-melter", wherein a high-temperature impact of metal melt and slag in one part of integrated device and plasma impact in other part of ones result in reliable, high specific productive, complete or near complete gasification of the organic components of wastes and melting of their metal and mineral constituents.

Term "solid wastes" is referred to all types of wastes, including that are not sorted by size and chemical composition:

1 ) industrial wastes - the used up tires, polyvinylchloride products, etc.;

2) municipal wastes - glass breakage, wood, dryed faecals, food remains, etc.;

3) special wastes - for example, medical wastes, which comprise the hazardous for human health or environment chemical species.

Term "the commercial, ecologically neutral products" is referred to:

1 ) synthetic gas (syn-gas) - gas mixture, which comprises mainly hydrogen, carbon monoxide, carbon dioxide and water and can be used as a high-caloric gas fuel in the electrochemical fuel cells (FC), gas turbines (GT), Internal Combustion Engines (ICE) or as a reagent for chemical and petrochemical industries; 2) chemically stable mineral slag in form of granules, fibres, etc. for the roads building, thermal insulation of buildings and other applications (pavement materials, water-permeable materials, gardening materials, ecologically-neutral cement, etc); 3) low-grade metal or metal alloys for subsequent treatment in metallurgy.

2. Discussion of the Prior Art

It is known a high-temperature waste treatment method, named "Thermoselect Process" (see description in F.J. Schweitzer, Thermoselect Process for the Outgassing and Gasification of Wastes, EF-Verlag fur Energie und Umwelttechnik, 1994, and the associated patents: DE 4130416, F23G 5/00, 1991 ; US 5282431 , F23G 5/00; US 5707230, F23D 1/12, 1998; US

5788723, C10J 3/20, 1998; US 5960722, F23G 5/12, 1999).

The essential stages of the "Thermoselect Process" are:

1 ) pressing of the unsorted solid wastes into bricks with definite geometry and size;

2) feeding of the bricks via heated (above 100 °C) charging channel into high-temperature (about 2000 °C) gasification zone;

3) bricks movement under the influence of gravity through high- temperature zone and formation of gas-permeable pile of the bricks. Pile basis is located at slag/gas interface, pile top is located near outlet of charging channel;

4) primary pyrolysis and gasification of the organic components (carbon- and hydrogen- containing) of wastes in oxygen-containing gas stream, which flows via bricks pile. Oxygen-containing gas mixture is supplied via lances under the gas/melt surface and into bricks pile zone;

5) maintaining of high temperature within operational range in gasification zone is provided by the exothermal chemical reactions (partial oxidation and shift reactions running at surface the bricks and at surface of the solid or liquid particles, floating in ascending gas stream) and supported by the gas burners (stand alone or combined with oxygen lances).

Some of the disadvantages of the "Thermoselect Process" are the following: 1 ) limited operational temperature in reaction zone - low specific (per volume of gasification zone) productivity. Maximal temperature in gasification zone can not be higher the theoretical thermodynamic limit - Adiabatic Isochoric Complete Combustion Temperature (AICCT), which does not exceed 2100 °K for majority of the gas and liquid hydrocarbon fuels under air combustion conditions. Mentioned inherent temperature constraint precludes to attain a high specific productivity of gasification process;

2) restrictions to scale-up the gasification process for compact tunable gasifiers, aimed to work at variable productivity, including low ones. For compact devices the heat transfer surface to reactor volume ratio is large, hence the specific thermal losses are high and stationary operation requires the special measures on heat losses reduction and additional thermal energy supply into reaction volume;

3) relatively high content of carbon dioxide and low content of hydrogen

- non optimal level of energy recovering. For standard (10 t/h) production line of "Thermoselect Process" a representative chemical composition of syn-gas is

- CO (63.4 vol.%), CO2 (7.1 vol.%), H2 (6.9 vol.%). Here an essential part of the carbon-containing species were completely oxidized and are useless for subsequent energy generation. For higher energy recovering it is necessary to perform partial oxidation of the wastes in regimes, which facilitate the maximization of carbon monoxide to carbon dioxide and hydrogen to water steam ratios.

Mentioned disadvantages of the thermal gasification methods in general and "Thermoselect Process" in particular were partially overcomed by D.R. Cohn, Surma J.E., Titus CH. [8]. Their method and device for "plasma-melt" wastes treatment has been selected as prototype for proposed invention. (See description of selected prototype in US patent US 6215678, H02M 007/06,

2001. Different modifications of selected prototype are described in the US patents 5666891 1997; 5756957 1998; 581 1752 1998; 5908564 1999; 6018471 2000; 6037560 2000; 6127645 2000; 6160238 2000.) According to prototype description, the solid wastes are charged into integrated "plasma reactor-melter" system above gas/slag interface, movement of the solid waste pieces thorough gasification zone is driven by gravity, waste pile is formed at surface of gas/slag interface, heating of slag/metal bath is performed by plasma, generated by graphite electrodes, and joule heat in slag/melt volume, oxygen-containing gas is supplied under the oxygen-deficit conditions (so called partial oxidation), syn-gas, liquid slag and melted metal are released from system.

Method is realized at integrated high temperature device, which comprises a common heat-resistant body, waste charging means, melted slag/metal bath in lower part of integrated system, plasma generator with plurality of the graphite electrodes ("arc plasma furnace") in upper part of unit, joule heater with another plurality of graphite electrodes ("electric melter") in lower part of unit, the means for oxygen supply, and the means for syn-gas, liquid slag and metal release.

Usage of arc plasma as a heater instead of the hydrocarbon-air burners provides higher operational temperature and stability of gasification thermal regime. Maximal temperature in plasma-chemical reaction zone can be varied

(upon needs) within range from 2500 to 5000 °C, which is unattainable in the prior art thermal gasifiers with the hydrocarbon-oxygen burners. High operational temperature and existence of a large number of chemically active radicals and ions in plasma result in essential intensification of the wastes pyrolysis and gasification processes.

Independent control over each plurality of electrodes permits to vary a level and location of thermal energy input and, hence, make it possible to change temperature both in gas-plasma phase and in slag/metal bath within wide range. Flexibility of plasma-based energy input control and management provides technical capabilities for tuning of "plasma-melt" gasifiers according to chemical composition of solid wastes and their total power scaling-up. The selected prototype of "plasma-melt" system provides higher (in comparison with "Thermoselect" process) quality of combustible syn-gas, suitable for energy effective utilization in gas turbines, electrochemical fuel cells and internal combustion engines. According to listed patents for prototype system, a representative chemical composition of syn-gas, produced from solid wastes in integrated "plasma-melt" system is - CO (44 vol.%), C02 (2 vol.%), H2 (43 vol.%). Comparison with a representative chemical composition of syngas, generated in "Thermoselect Process", shows that both CO/CO₂ and H₂/H₂0 ratios are increased, consequently, a quality of syn-gas is improved.

The selected prototype demonstrate the benefits of using "plasma-melt" gasification in comparison with "thermal-melt" gasification - higher operational temperature, capability to tune operational regime parameters, to provide conversion of solid wastes into useful gas with enriched content of the combustible gases (carbon monoxide and hydrogen) and into stable, non- leachable solid products at a single location, and scaling-up total power of integrated unit.

However, the selected prototype of "plasma-melt" gasification have the following disadvantages:

1 ) wastes are charged above gas/slag interface. This common feature of prototype ("arc plasma - melter") and the other prior art thermal gasification systems (i.e. "Thermoselect Process") results in three drawbacks:

a) limited heat and mass transfer rates in gasification zone and melt/slag bath - low overall productivity of gasification process for given geometrical and thermal boundary conditions. In prior art devices (both in the thermal - DE Pat. No. 4,130,416 and plasma- melt gasification units - U.S. Pat. No. 6,215,678) the pieces of solid waste are feed into high-temperature gasification zone via charging opening, located above the gas/slag interface. Waste pieces form a gas permeable bed, which are sinking into slag bath gradually under force of their own weight. This passive, self-driving mode of mass and heat transfer between solid waste pieces and liquid slag is not utmost intensive. The opportunities of the forced modes for waste moving within gasification zone and for heat and mass transfer intensification inside of melt bath are not used; b) low thermal conductivity of gas-plasma phase - low rate of thermal pyrolysis in brick pile gasification zone. Major part of pyrolysis process occurs in a gas-permeable pile, formed by waste pieces lying down between intake point and molten slag surface. The "bottleneck" for a heat transfer from high-temperature flame or plasma zone to waste piece surface is a thermal conductivity of gas mixture, which is lower then thermal conductivity of molten slag or metal. Thermal conductivity coefficient for air is (λ_ai_r ~ 0.04 W/(πτK)) much lower then thermal conductivity coefficient of liquid slag/metal melt phase (λ_mβιt * 1.3 + 15 W/(m K)); c) limited length of gasification zone for given operational temperature - incomplete gasification of the small size pyrolized particles. The small size (less then 1 mm) pyrolized particles (carbon soot, dusts, fine oil drops, tars, etc.), formed in the brick pile gazification zone, are carried out by ascending stream of syn-gas. Their residence time for given operational temperature can be insufficient for complete gasification. In this case the syngas contains a lot of impurities, which require additional resources for their removal. In engineering practice for minimization of the ungasified particles concentration in syn-gas outlet stream a secondary gasification zone is introduced into the delay chamber above the gasification bed (see, U.S. Pat.

No. 5,960,722);

2) non optimal using of oxygen-containg gas for pyrolysis and partial oxidation. A gaseous oxygen, supplied into reactor at a point proximate to slag material, does not participate in the partial oxidation processes, which can take place within the molten metal and slag phases, and does not contribute to an intensification of the heat and mass transfer processes inside of the liquid layers. 3) usage of the graphite electrodes for plasma generation is ineffective for two reasons.

a) life time of expendable carbon electrodes, used in prior art patents (U.S. Pat. No. 6, 215,678 and related patents), is limited, so it is necessary to provide periodically a technically complicated, time and money consuming replacement of electrodes. This feature decreases the overall productivity of plasma gasification and increases the operational costs, b) plurality of electrodes, used for thermal management and plasmachemical conversion, require a electrically complicated and energy-consumed system of electric power supply control. This feature decreases a simplicity of plasma generator control and management.

While the mentioned prior art attempts have been useful, there remains a need in a new art of waste gasification and resources recovery with the improved characteristics of waste conversion products, the enhanced technical

(scalability, serviceability) and economical characteristics of gasification unit and more stable and tunable operation of waste treatment process.

SUMMARY OF THE INVENTION

Problems to be Solved by the Invention

An objective of the present invention is to solve the above-described problems of the related prior art and to provide the following specific advantages:

1 ) to increase the specific (per volume unit of gasification zone) productivity of waste treatment and resources recovery via increasing of pyrolysis rate and providing forced (instead of passive, self-driving in prior art) mode of the heat and mass transfer processes within the molten slag and metal phases; 2) to improve chemical quality of generated syn-gas (to enrich syn-gas with hydrogen) via decreasing a number of the ungasified particles (soots, tars or aerosols) in syn-gas at outlet of gasification unit;

3) to allow tunable (for different chemical compositions of wastes), scalable (for different total total power of unit) and economical operation in a wide range of the operational and performance conditions, including at relatively low total power and compact unit scales;

4) to exclude influence of electrode material on thermal balance and chemical processes inside of integrated system;

5) to increase time of permanent (without interruptions on electrode exchange) operation of the plasma generators;

6) to increase repairability and life-time of internal surface of integrated gasification and slag/metal pool unit, subjected to molten liquid attack;

7) to provide temperature management of slag/metal bath for the wastes with different energy content.

Means for Solving the Problems

For attaining of the mentioned goals, a method of waste treatment is proposed. Method is based on treatment of the solid wastes in high temperature molten slag/metal bath and high temperature plasma jets with a supply of the wastes and the oxygen-containing gases under gas/slag interface in integrated "plasma-melt" device. For method implementation it is proposed a device, which contains a cooled common body of high temperature gasification reactor, a cooled channel for wastes charging, an electrodeless plasmatrons for water steam plasma jets generation, the near- or super-sonic lances for oxygen- and/or steam-containing gas blowing off a molten slag/metal bath, the devices for release of syn-gas, molten metal and molten slag. BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic drawing of the basic stages of proposed method according to this invention.

FIG.2 is a schematic drawing of a general view of proposed device according to this invention.

FIG.3 is a schematic drawing of a horizontal cross-section view of the plasma jets arrangement according to this invention.

FIG.4 is a schematic drawing of a horizontal cross-section view of the oxygen- and/or steam-containing gas lances arrangement according to this invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG.1 illustrates a flowsheet of the basic consequent-parallel stages of proposed method in accordance with the present invention:

1 - waste pressing into bricks,

2 - forced, controlled, consequent supply of the bricked wastes under the metal melt surface, 3 - controlled supply of the oxygen-containing near- or super-sonic gas jet via lances under the melt surface,

4 - the primary processes of the pyrolysis, gasification and heterogeneous oxidation reactions in molten metal,

5 - the secondary processes of the heterogeneous re reaction in slag- gas emulsion,

6 - the tertiary processes of the plasma- and gas-phase chemical reactions, 7 - the fourth processes of the afterglow chemical reactions and chemical composition stabilization of syn-gas before exit from integrated "plasma-melt" gasification unit

8 - quenching of syn-gas 9 - fine purification of syn-gas from the harmful or undesirable particles.

At FIG.2 a general view of device in accordance with the present invention is shown. Device comprises:

1 - cooled (preferably by water) body, which is common for melt bath and plasmachemical reactor,

2 - apparatus for charging of the unsorted solid wastes of different kind,

3 - press for waste compressing and briquetting,

4 - pusher for horizontal moving of waste bricks to waste charging channel,

5 - pusher for vertical moving of waste bricks through waste charging channel,

6 -cooled (preferably by water) channel for waste bricks charging under metal melt surface, 7 - gas/slag interface (in absence of oxygen blowing off),

8 - molten slag/metal interface (in absence of oxygen blowing off),

9 - electrodeless plasmatrons for plasma jets generation,

10 - gas lances for near- or super-sonic (preferably) blowing off the molten bath, 1 1 - release channel for syn-gas,

12 - release channel for molten metal,

13 - valve for molten metal release,

14 - inductive heater,

15 - channel for molten slag pouring, 16 - vessel for molten slag treatment,

17 - release channel for molten slag,

18 - valve for molten slag release,

19 - inductive heater. At FIG.3 a layout of the electrodless plasmatron outlet cross-sections and the directions of plasma jets movements are shown for horizontal cross- section A-A from FIG.1.

At FIG.4 a layout of the gas lance sections and the directions of supersonic gas jets are shown for horizontal cross-section B-B from FIG.1.

Proposed method is put into effect by the following way:

1 ) unsorted waste is pressed into bricks with definite shape and size

(process is shown by number 1 at FIG.1 );

2) the bricks under forced actions of the horizontal and vertical pushers are consecutively supplied into high temperature zone through waste charging channel (process is shown by number 2 at FIG.1 );

3) pure oxygen (preferably) or oxygen-containing gas mixture and/or water steam is supplied under molten slag/metal interface (process is shown by number 3 at FIG.1 );

4) primary pyrolysis and gasification of the organic components of the wastes and melting of the inorganic components of the wastes in metal melt (process is shown by number 4 at FIG.1 ). As metal can be used an iron (preferably) or other metal or metallic alloy, which dissolves carbon in molten state;

5) secondary pyrolysis and gasification of the organic components of wastes in molten slag (process is shown by number 5 at FIG.1 );

6) tertiary pyrolysis and gasification of the organic components of wastes in plasma (process is shown by number 6 at FIG.1 ); 7) forth pyrolysis and gasification of the neutral particles and recombination of the charged particles in gas (process is shown by number 7 at FIG.1 );

8) quenching of syn-gas (process is shown by number 8 at FIG.1 );

9) fine purification of syn-gas from the harmful or undesirable species (process is shown by number 9 at FIG.1 ).

In comparison with prototype the proposed method has the following principal distinctions:

1. high temperature (2500 - 5000 °C) plasma is generated by an electrodeless plasmatrons, for example - by the High Frequency or MicroWave discharges. Plasma is generated in form of the plasma jets. An intensity (flowrate) and the thermochemical parameters of plasma jet can be managed both in space and time. Shown peculiarity of proposed method is absent in prototype, where plasma arc has the fixed (for given geometry of device) thermochemical parameters, a fixed location and does not form a macroscopic convective movement of plasma.

In proposed invention the plasmatrons carry out two functions: (1 ) generate chemically active radicals, ions and excited neutral particles. These particles provide higher (in comparison with gas phase) rate of the pyrolysis and gasification chemical reactions; (2) form convective movement of the plasma jets. A convective movement of plasma in direction opposite to direction of ascending syn-gas increases a residence time of fine particles (soots, tars, aerosols, etc.) in high-temperature zone of the intensive plasma- and gas- phase chemical reactions. Mentioned feature of plasma jets according to invention increases chemical quality of syn-gas (reduce ratio of the ungasified particles) and is absent in propotype of invention.

Using of the electrodeless plasma generators permit to attain the forth and fifth technical goals of proposed invention. Absence of the electrodes does not influence on temperature of plasma (it can be varied within requested temperature range - as well as in prototype) and permits to exclude the problems of electrode erosion/damage and their influence on energy balance and chemical composition of plasma. Using proposed invention it is possible to increase an un-interrupted time of plasmatron operation and exclude necessity to exchange the electrodes.

High temperature of plasma jet and possibility to manage a thermal power, supplied into gasification zones of proposed device, make it possible to scale-up and tune the operation parameters in dependence of a chemical composition of the solid wastes and a requested total productivity of waste treatment unit. Using proposed method it can be possible to built the compact "plasma-melt" devices with high specific rate and at the same time relatively low total productivity.

2. point, wherein the waste bricks enter into high-temperature zone, is located below molten slag/metal interface.

3. waste charging channel is cooled, preferably by water.

The second and third mentioned features of proposed invention permit to charge the waste bricks directly into molten metal under compulsory conditions and with controlled rate. High value of thermal conductivity of melt (10-100 times higher then in gas phase) permits to speed-up a waste brick heating up, hence to accelerate a pyrolysis rate and facilitate attaining of the first goal - to increase overall rate of gasification. Controlled manner of brick before its splitting into the smaller pieces due to chemical pyrolysis and thermal stresses minimizes the fluctuations of chemical composition of syn-gas and enhance stability of waste treatment unit operation.

4a) oxygen is blowed into melt phase via a system of the lances, which provide the large-scale convective flows of melt phase in horizontal direction and intensive jumbling of melt phase in vertical direction; 4b) each lance forms near- or super-sonic oxygen jet, which provides active missing up of melt, but does not "punch" slag/melt bath (gaseous jet core does not go out at gas/slag interface) and does not contact with the internal surfaces of high-temperature reactor body.

Fourth distinguished feature of proposed method serve also for attaining the first goal - to increase overall waste treatment rate via intensification of the heat and mass transfer processes in the molten slag and metal phases. Both the large-scale convective flow, induced by oxygen jets, and small-scale mixing, caused by the gaseous products of pyrolysis (carbon monoxide, metahe, hydrogen, etc.) provide more intensive heat- and mass transfer within melt phase in comparison with prototype.

5. pyrolysis and gasification of the wastes is carried out in regular mode in the four media (zones) in consecutive order (see FIG.1 ):

5. a) pyrolysis and primary gasification of the organic components and melting of the metal and mineral components of large pieces of waste bricks is performed in bottom zone of integrated unit at temperature 1600 - 2000 °C. Lower zone consists mainly of metal melt;

5b) secondary gasification of the organic component of the medium and small pieces of waste, which come to the gas/slag interface, is performed in middle zone at temperature 2000 - 2500 °C. Middle zone consists mainly of slag-gas emulsion;

5c) tertiary gasification of the small soot, tar and aerosol particles is performed in water steam plasma at temperature 2500 - 5000 °C;

5d) fourth gasification of the residuals is performed in gas phase at temperature about 1000 °C.

According to fifth distinguished feature of proposed method each waste piece passes through four high-temperature zones, where the intensive chemical reactions occur, - in metal melt, in slag melt, in plasma, in gas. Presence of the plasma jets, waste and oxygen supply under metal melt surface provide a regular, consecutive gasification of wastes in the four high- temperature zones. These features are absent in propotype of proposed invention and facilitate a more complete gasification of the wastes, assist to reduce the loads on subsequent gas purification systems from ungasified particles.

6. cooling of proposed integrated system is performed by forced circulation of coolant, preferably water, along system of the easily exchangeable tubes, separated by the insets made of refractory material, preferably aluminum oxytrinitride (so called "cold crucible" technology). High thermal loads at internal surface of integrated device from plasma and melt phase result in accelerated degradation of the ordinary refractory ceramic materials. The "cold crucible" principle was proposed earlier for plasma- chemical and nuclear applications. In proposed invention this principle is used for the new applications - waste treatment and resources recovery. Using of a forced cooling of internal surface of integrated device provide solution of attaining of a sixth objective - to increase thermal and construction resistance against high-temperature impact of plasma and melt.

Schematic representation of proposed device for technical implementation of proposed method is shown at FIG.2, 3, and 4.

Device contains a common water-cooled body ("cold crucible") 1 , waste charging unit 2 with press 3 for waste briquetting, pusher 4 for horizontal movement of the bricks toward charging channel, water-cooled charging channel 6 for vertical supply of the bricks under surface 8 of a molten slag/metal phase interface (in absence of oxygen blowing), electrodeless plasmatrons 9, located above surface 7 of a gas/slag phase interface (in absence of oxygen blowing), oxygen lances 10, syn-gas discharge channel 1 1 , molten metal sink channel 1 1 with valve 13 and inductive heater 14, channel 15 for casting of molten slag, molten slag treatment vessel 16, molten slag sink channel 17 with valve 18 and inductive heater 19. For molten slag/metal bath blowing a pure oxygen or oxygen-containing and or/water steam gas mixture can be used in order to perform partial oxidation of the carbon-containing component of wastes.

According to proposed invention, for the energy balance management or for the syn-gas chemical composition control purposes a gas mixture for slag/metal bath blowing off can contain a water steam. Presence of water steam in gas mixture for blowing results in hydrogen enrichment of syn-gas due to steam conversion reactions, for example - C+H₂O -» CO + H, . Endothermal nature of mentioned reactions permits to manage of temperature during treatment of the wastes with high content for energy (for example, used automobile tires).

Proposed location of the outlet cross sections of the nozzles and spatial orientation of the lances for blowing provide more intensive (in comparison with prototype, where the special technical means for heat and mass transfer intensification in molten slag/metal phase are absent) horizontal mixing of metal and slag melt. At least, a one lance is necessary for mentioned effect implementation. The multiply lances, for example, three lances are preferable for provision of the uniform (over entire slag/metal volume) conditions for pyrolysis, gasification and melting (see FIG.1 cross section BB). Simultaneous operation of the lances provides a large scale flow of melt in direction, for example, counter clockwise.

For intensification of horizontal mixing of slag/metal bath in preferred embodiment (see FIG.4):

1. the axes of all lances are arranged in horizontal plane and are directed along the sides of equilateral triangle, inscribed into circle horizontal cross section of internal surface of cooled, common body,

2. a blowing intensity in lance system is regulated in such a manner, that mass flowrate of each lance is wavy varied and the flowrate oscillations in the different adjacent lances have phase shift 2π/n , where n is a number of lances, located in the edges of polygon. For preferred embodiment a phase shift is 2π 3 in accordance to proposed invention.

For mixing intensification in vertical direction a slag/melt bath blowing is performed by near- or super-sonic gas jets.

In order to exclude contact of gas jet with bottom internal surface of water-cooled body 1 and to eliminate degradation or burning through of bottom refractory layer the lance axes are located at distance no less then nine nozzle diameter (at outlet cross section) from said bottom layer.

In order to avoid erosion or burning through of a lateral surface of water- cooled body 1 a mass flowrate via each lance should not exceed of limiting value, which is equal to

where V_m is a total mass flowrate (kg/sec) via one lance, h is a length of triangle side for preferred embodiment, w_g is gas velocity (m/sec) at exit cross section of nozzle.

Proposed location of the outlet cross sections of the plasmatrons and spatial orientation of the plasma jets provide more intensive (in comparison with prototype, where the special technical means for heat and mass transfer intensification in gas-plasma phase are absent) breaking up and turbulisation of the ascending syn-gas flows with the small particles (soots, tars or aerosols) unreacted in the metal and slag zones. Breaking up and turbulization of syngas flow is necessary for increasing of residence time of small particles in zone of intensive plasmo- and gas-phase reactions. At least, a one electrodeless generator of plasma jet (plasmatron) is necessary for mentioned effect implementation. The multiply plasmatrons, for example, three electrodeless plasmatons (see FIG.1 cross section AA) are preferable to increase surface of ascending gas flows treatment by plasma jets and to provide uniform (over total gas-plasma volume) conditions for running of the gas- and plasma pyrolysis and gasification processes. Simultaneous operation of the three plasmatrons should provide a circular convective flow of plasma-gas mixtures in direction opposite to swirling direction of slag-melt bath, for example, clockwise.

In preferred embodiment (see FIG.3) of proposed device the all exit cross sections of the plasmatrons are arranged (in projection on horizontal plane) at the edges of equilateral triangle, embedded into circle. Axis of each plasmatron is arranged so, that the angle between plasma jet movement and horizontal slag surface will be in range between 60 and 90 degree.

Proposed device operates in the following way:

Unsorted waste is loaded into charging unit 2, where bricks are formed by the press 3. Shaped brick of waste is moved by pusher 4 towards vertical charging channel 6. Pusher 5 move said brick and the previously charged bricks along charging channel down into metal melt zone with velocity, defined by operator. Brick supply is performed with an operator-defined speed, which provides a complete or near complete dissolution of the carbon-containing components, a melting of the mineral and metal components in the said metal melt and permits to avoid early floating up of the large pieces of waste at slag melt surface. Velocity of waste bricks supply is controlled so, that mass fraction of carbon in metal melt will be not more then a carbon dissolution limit in molten metal. Any metal or metal alloy, whose liquid phase dissolves carbon, can be used in proposed method. In preferable embodiment of proposed invention a preferable metal is iron, and mass fraction of carbon, dissolved in iron, should not exceed three per cent.

Under influence of high temperature and chemical activity of metal melt a brick of waste, exiting from charging channel, is quickly (in comparison with heating up rate in a gas or plasma phase at the same temperature) heated up due to high thermal conductivity of melt and is breakdown into the smaller fragments. At surface of the said fragments, an intensive melting of the mineral and metal components of waste, carbon dissolution in molten metal, pyrolysis and primary gasification of organic components of waste are performed. Under influence of said physico-chemical factors a subsequent splitting up of waste pieces into the small (around 1 cm) pieces occur. Oxygen, supplied via lances, oxidizes molten iron and dissolved carbon. Formed oxides - gaseous carbon oxides and molten iron oxides - floating up in slag zone and provide intensive mixing of molten metal in vertical direction. Besides barbotage of the melt bath, the gas bubbles form extensive gas/melt interface, where heterogeneous chemical, heat and mass transfer processes take place. Mentioned processes create the effective conditions for breakdown, pyrolysis and gasification of the next brick, exiting from charging channel. Small particles of waste, which were not gasified in metal melt zone, are floating up into slag zone and slag-gas emulsion, where secondary gasification and subsequent diminishing of the unreacted particles occur.

The fine (with size lesser then 1 mm) particles of soot, tar or aerosol, formed in slag zone, are catched up by ascending flow of syn-gas and move into plasma-phase zone. In plasma a tertiary gasification occurs and the main role is played by the plasmachemical reactions with participation of the radicals and ions.

Fourth gas-phase gasification takes place in upper part of proposed device. Here a high (about 1000 °C) temperature is maintained and residence time of the submicron particles is enough for total or nearly total reactions of partial oxidation ( 2CH₄ + 3O, → 2CO + 4H₂O ) or shift ( C + H₂O → CO + H₂ ).

According to accumulation in reactor, a mineral slag is decanting via channel 15 into vessel 16, where slag homogenization and, upon necessity, special treatment occur.

Upon operator command, a valve 18 is opened and a slag is released via sink channel 17, heated by heater 19. Molten slag treatment into commercial products (granules, fibres, etc.) is made in appropriate device, which were not shown at figures of proposed invention.

Upon operator command, a valve 13 is opened and a molten metal is released via sink channel 12, heated by heater 14. Molten metal is released into special container for transportation and subsequent treatment. Appropriate treatment of metal (freezing, blending, etc.) takes place in devices, which do not shown at figures of proposed invention.

Claims

1. Method for plasma-melt treatment of the solid wastes and resources recovery, which includes a slag/metal heating by plasma, charging of wastes into reactor-gasificator, running of multi-step gasification, oxygen- containing gas supply into pyrolysis and gasification zone, release of forming syn-gas, molten metal and slag from reactor for subsequent processing into the valuable commercial products. Method is distinguished by the following:

• preliminary briquetted wastes are forcedly supplied below a molten slag/metal interface via cooled channel,

• plasma jets are generated by electrodeless plasmatrons,

• oxygen-containing gas is supplied horizontally below a molten sulg/metal interface.

2. Method according to claiml , where wastes are loaded with mass flowrate so, that a carbon to metal mass ratio does not exceed a thermodynamically equilibrium value for dissolved carbon in molten metal. For preferred embodiment, where iron is used, the carbon to iron mass ratio should not exceed 0.03.

3. Method according to claim 1 , where pure gaseous oxygen or air and/or water steam gas mixtures are used as an oxygen-containing mixtures.

4. Method according to claim 1 , where said oxygen-containing gas is supplied with tunable volume flowrate, which is sufficient to partial oxidation of the organic components of wastes, but does not sufficient to the complete oxidation of the ones.

5. Method of clams 1 , 3, 4 where said oxygen-containing gas is supplied in a near- or super-sonic regime via at least one lance.

6. Method according to claims 1 , 3, 4, 5 where volume flowrate of said oxygen-containing gas per each lance does not exceed critical value equals to V„, ≤ 578 - h³ iw„

where V_m is a total mass flowrate (kg/sec) via one lance, h (m) is a distance between two lances for preferred embodiment, w_g is gas velocity (m/sec) at exit cross section of nozzle.

7. Method according to claims 1-6, where volume flowrate via each lance is wavy varied (preferably sinusoidally) and the flowrate oscillations in the different adjacent lances have phase shift 2π/n , where n is a number of lances, located in the edges of equilateral polygon, inscribed into circle of inner surface of reactor body. For preferred embodiment a phase shift is 2πβ in accordance to proposed invention.

8. Method according to claims 1 -7, where high temperature plasma is generated as plasma jet.

9. Method according to claims 1-8, where the plasma jet flows are directed to slag/metal interface at angle in range 60-90 degrees and opposite to ascending syn-gas flow.

10. Device for plasma-melt treatment of solid wastes, including the municipal, industrial, special wastes, used tires, and for resources regeneration, comprising a common water-cooled body with a

• means for waste charging, slag/metal bath in bottom part of integrated unit,

• plasma generator in upper part of integrated unit,

• the means for oxygen-containing gas supply,

• the means for syn-gas release, metal melt release and slag melt release

• where means for the solid wastes charging is performed as a bin with a means for the briquettes forming; • means for sequential supply of the bricks into vertical water-cooled charging channel, whose bottom orifice is arranged below slag/metal interface;

• plasma generator is made as at least one elecrodeless plasmatron (in preferred embodiment - three plasmatrons);

• means for oxygen-containing gas feeding is made as at least one horizontal lance, whose outlet nozzle is arranged below slag/metal interface;

1 1. Device according to claims 10, where number of the lances is equal to three.

12. Device according to claims 10, 1 1 , where the outlet nozzles of the lances, arranged below slag/metal interface, are disposed at distance not less then nine diameters (of nozzle in outlet cross section) higher then bottom internal surface of common body.

13. Device according to claim 10, where the axes of the all lances are horizontal and aligned along sides of equilateral triangle, inscribed into circle of internal lateral surface of unit body. Movement of the super-sonic jets provides macroscopic swirling of slag-metal emulsion in preferred direction, for example, counter clockwise.

14. Device according to claim 10, where a number of the electrodless plasmatrons is equal three.

15. Device according to claim 10, where the outlet cross sections of the electrodeless plasmatrons are located above gas/slag interface.

16. Device according to claim 10, where the electrodeless plasmatron axes are arranged in vertical plane under angle in range 60-90 degrees to slag surface and in horizontal plane the plasmatron axes are aligned along the sides of equilateral triangle, inscribed into circle of internal lateral surface of waste treatment unit body. Movement of the plasma jets provides macroscopic swirling of plasma-gas media in preferred direction, opposite to moving of slag/melt swirling, for example, clockwise.

17. Device according to claim 10, where body has two layers. External layer is made of system of the water-cooled metal tubes. Internal layer is made of refractory ceramic materials, comprising mainly the oxides and nitrides of aluminium and of the other refractory materials with a small thermal expansion coefficient.