WO2023286101A1

WO2023286101A1 - Apparatus and corresponding method for cooling and recovering energy from a flow of hot material, in particular slag

Info

Publication number: WO2023286101A1
Application number: PCT/IT2022/050208
Authority: WO
Inventors: Gioacchino Nardin
Original assignee: Ibis Engineering Srl
Current assignee: Ibis Engineering Srl
Priority date: 2021-07-15
Filing date: 2022-07-14
Publication date: 2023-01-19
Anticipated expiration: 2024-01-15
Also published as: IT202100018665A1

Abstract

Apparatus (100) for cooling and recovering energy from a flow of molten or partly molten hot material (13) having a high thermal energy. Said apparatus (100) structurally comprises a technical volume (14) kept in depression and provided with an inlet opening (114) for the introduction of said hot material (13) and an outlet opening (214) for the extraction of a flow of cooled material (19) having a thermal energy lower than that of said flow of hot material (13). Said apparatus (100) functionally performs the controlled cooling of the hot material (13) with zero environmental impact and with energy recovery with a supply that can be continuous.

Description

“APPARATUS AND CORRESPONDING METHOD FOR COOLING AND RECOVERING ENERGY FROM A FLOW OF HOT MATERIAL, IN

PARTICULAR SLAG”

FIELD OF THE INVENTION

The present invention concerns an apparatus for cooling materials with energy recovery, in particular thermal recovery, and a corresponding method.

In particular, the present invention is applied in all activities in which flows of molten or partly molten materials are treated which have a high thermal energy and high temperature and in particular, but not exclusively, in the case where cooling said materials may possibly cause flows of gaseous and dusty, polluting and/or dangerous fluids.

Typical examples, although taken here by way of example of all cases that have similar, comparable or identical characteristics, are found in the chemical, pharmaceutical and steel industry in general.

Hereafter, to simplify the description and facilitate understanding of the invention, reference will be made to the steel industry, in particular to a specific part of steel production activity with an electric furnace.

BACKGROUND OF THE INVENTION

It is known that in steel production activity with an electric furnace the so-called molten gray slag is produced, which makes up about 13÷14% of the steel produced.

Normally, the slag is discharged into pits which are equipped with lateral barriers in order to limit the dispersion of dusts.

The problems related to gray slag also occur in the case of white slag from the refining process, even if the latter is present in a smaller quantity given the same production cycle.

The cooled white slag has a similar appearance to lime, it is slightly abrasive, can be transported pneumatically and is normally recycled inside the process.

In this case too, it is not possible to sufficiently counteract the air dispersion connected to the slag, so that the air and the environment are polluted.

Various systems or plants for the rapid cooling of slag are known.

One of these provides the rapid cooling of the melted slag in a granulation plant using large quantities of water. Alternatively, cooling is obtained more slowly in special pits, with the possible use of small quantities of cooling water or by immersing the entire pot that contains the waste directly into the water.

However, it is known that when the slag comes into direct contact with the water, in addition to generating safety problems due to the risk of violent expansion of the vaporized water, the enthalpy content contained in it is dissipated.

Another known cooling system implemented at a semi-industrial level provides an atomization process with rotating disk means configured to granulate the slag, obtaining a material in the vitreous phase. Subsequently, the heat of the slag is recovered at low enthalpy.

A recovery plant has also been designed which provides the dry granulation of the slag, eliminating its contact with the cooling water, at the same time actuating a controlled and repeatable cooling according to the type of slag to be treated.

In this case, a mechanical crushing process is used by means of counter-rotating drums. The drums are water-cooled internally, and this allows the rapid cooling of the slag by contact, with a consequent vitrifying effect. However, when it exits the drums, the slag is normally still semi-liquid.

As it falls, the slag is cooled by a variable number of air nozzles. Finally, a collection system below conveys all the material, now recyclable, into a storage compartment.

This system has several limitations: it is a delicate and complex system from a plant point of view, the drums can be dirtied, it does not perform energy recovery, cooling times are short, in the order of 15-30 seconds, etc.

A similar pilot plant known in the state of the art has rotating rollers indirectly cooled with a coolant which flows inside the drums, normally made of copper. The molten slag is made to cooperate with the external part of the drums. This process tends to achieve a dry granulation, cooling the slag indirectly with water with an intermittent thermal recovery of less than or around 30%.

Energy recovery systems are also known starting from previously granulated slag, such as the one described in WO 2018/023101 A2 which, however, is not able to treat flows of molten or partly molten slag, so that energy recovery is very limited and discontinuous.

The main difference between pit and pot slagging is the cooling mode. In the case of the pot, that is, the container of the slag, there is a slow cooling, guaranteed by the refractories. In fact, it takes about 24 hours to give the slag time to solidify, before being able to safely move the pot itself.

On the contrary, if a pit is used, there is a rapid cooling of the slag, in the air or with water sprays, which limits its disintegration. Studies have shown how the reactivity of the slag in contact with water increases, even naturally, when rapid cooling is applied.

All the apparatuses that constitute the current state of the art at a semi-industrial, prototype or experimental level are inadequate for continuous industrial use. This inadequacy derives from excessive complexity, poor reliability, the absence of a considerable and continuous recovery of the enthalpy content, the significant impact in terms of dust dispersion, the insufficient degree of vitrification of gray slag and the poor efficiency of cooling.

The environmental impact generated by this practice often entails the imposition, by the control bodies, to discharge the waste in closed and dedicated warehouses. This solution entails high investments without preventing the diffusion of gas and dusts which constitute potential health hazards for the workers working inside the warehouses.

Furthermore, energy recovery is scarce and, in any case, discontinuous and of little interest.

The state of the art is therefore not adequate for the energy and environmental transition targets, in particular according to the Road Map 2050, and the actions envisaged by the Next Generation EU in terms of energy efficiency and environmental protection. There is therefore a need to perfect an apparatus for cooling and energy recovery, in particular thermal, which can overcome at least one of the disadvantages of the state of the art.

In particular, one purpose of the present invention is to provide a cooling and energy recovery apparatus starting from materials with a high enthalpy content and at high temperatures, for example which carries out both the solidification and also the cooling of the molten slag, allowing to avoid the environmental impact, in particular with reference to dusts, and to optionally carry out the energy recovery of important values of thermal energies otherwise dispersed and to modulate them according to suitably managed tapping criteria in order to continuously feed an internal or external user machine, and to carry out the vitrification of at least part of the slag for the purpose of volumetric stabilization, over time, to facilitate the recycling thereof.

Another purpose of the present invention is to reduce the local environmental impact, to possibly improve energy recovery, to reduce C02 emissions in relation to the use of the thermal energy recovered in terms of thermal/electrical energy and in cogeneration, and finally, to respond to the aims of the circular economy, improving the quality of the slag and air.

The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.

SUMMARY OF THE INVENTION

The present invention is set forth and characterized in the independent claims. The dependent claims describe other characteristics of the present invention or variants to the main inventive idea.

The apparatus according to the present invention is suitable to carry out a rapid solidification and a controlled cooling of a flow of hot material at high temperature which is in a molten or partly molten state, hereafter also semi-molten, such as for example slag. At the same time, this apparatus allows to achieve an energy recovery in a closed environment, advantageously put in depression, from which gases and toxic polluting dusts that are generated are extracted, filtered and possibly controlled.

Here and in the following, by molten material we mean a material in a liquid state, because all its components have exceeded their melting temperature. By partly molten material we mean a material in which some of its components have exceeded their melting temperature, while others are still in a solid state because they have not exceeded their melting temperature, so that the material has the appearance of a heterogeneous amalgam.

In general, the apparatus according to the present invention can be used in various fields of industrial production which involve the production or the presence of molten or partly molten hot materials, which have a high content of thermal energy and high temperatures, which have to be cooled and which, during the cooling steps, and also subsequently, generate diffuse emissions of gaseous, dusty and/or polluting fluids.

By high content of thermal energy we mean an energy content capable of generating a recovered average thermal power no lower than 300 kW. By high temperature we mean a value equal to, around or above the melting temperature of the hot material. In the case of the slag, such value is comprised between about 1000°C and about 2000°C, preferably between about 1300°C and about 1700°C, even more preferably between about 1400°C and about 1600°C. The apparatus according to the present invention, for cooling and recovering energy from a flow of hot material having a high thermal energy and a high temperature comprises a technical volume provided with an inlet opening for introducing the hot material and a discharge opening for extracting a flow of cooled material having a thermal energy lower than that of the flow of hot material.

According to one aspect of the present invention, the apparatus also comprises a cooling and thermal recovery unit disposed at least partly inside the technical volume and provided with a plurality of thermal extraction means configured to come into contact with the hot material, both in order to cool it and also to extract at least part of the thermal energy contained therein in a continuous and managed manner. The term “thermal energy” is understood to also include the latent heat from the liquid-solid phase change.

According to another aspect of the present invention, the thermal extraction means are positioned in a vertically staggered succession, starting from a position below the inlet opening to a position in correspondence with the discharge opening. In other words, the thermal extraction means are disposed according to a stepped configuration, that is, in steps.

According to another aspect of the present invention, the thermal extraction means comprise fixed plates made of thermo-conductive material provided with respective heat exchangers, possibly also for energy recovery, inside which a heat transfer fluid is flowing. The heat exchangers extract thermal energy from the fixed plates, which in turn subtract it from the slag by conduction.

The heat transfer fluid can be monophasic or biphasic. In particular, the heat transfer fluid can be a liquid such as hot or superheated water, or diathermic oil, water vapor, or a gas such as air, nitrogen or carbon dioxide under pressure.

According to one formulation of the invention, the fixed plates, known as fixed bars, are positioned in steps in a downward configuration from the inlet opening to the outlet opening. Advantageously, the hot material comes into contact with the upper surfaces of the fixed plates yielding, by conduction, high thermal flows.

According to another aspect of the present invention, the fixed plates can be all the same or be in groups of equal fixed plates, since different groups can be tasked with exchanging heat at temperatures that are defined differently on each occasion, in order to achieve determinate thermal flows. According to another aspect of the present invention, the fixed plates comprise at least a first group of upper fixed plates, or rapid cooling plates, which have a high thermal conductivity coefficient and are located in a high initial part of the technical volume close to the inlet opening, and at least a second group of lower fixed plates, or thermal storage plates, which have a high thermal storage capacity and are located downstream of the upper fixed plates up to a low end part of the technical volume close to the discharge opening.

The first group of fixed plates configures a grid for the rapid solidification of the hot material, which in the case of slag causes a thermal shock on it and allows to carry out a first thermal extraction from the hot material. The rapid solidification grid carries out the rapid cooling of the slag and its solidification from an example temperature of about 1400°C to a temperature not higher than a desired temperature of, by way of example but not definitively, around 850°C, allowing an important energy recovery. According to requirements, this temperature can be higher or lower. Furthermore, the cooling by conduction determines a rapid solidification of the slag disposed on the upper fixed plates with important phenomena of vitrification and volumetric stabilization. Overall, in terms of number, conformation and contact surface with the slag the fixed plates are, advantageously although not necessarily, sized in order to bring the solidified slag at exit from the technical volume to a temperature of around 300°C, or in any case to a desired and defined temperature.

The second group of fixed plates configures a grid for cooling the partly solidified slag with extraction of the thermal content, provided with inertial thermal accumulations constituted by the same mass which the lower fixed plates are made of. The fixed plates as a whole, but in particular the lower fixed plates, constitute a thermal accumulation useful to feed an internal or external user machine with continuity and with managed criteria, even in the absence of hot material inside the apparatus and during the phases of waiting for the next hot material.

According to another aspect of the present invention, the upper fixed plates are provided with heat exchangers advantageously located in direct contact with a lower surface thereof, while the lower fixed plates are provided with heat exchangers made in their own body. Advantageously, at least in the slag case study, the upper plates are kept at an example temperature of about 100°C in the case of hot water heat transfer fluid.

According to the invention, the lower fixed plates are characterized by a thermal accumulation capable of storing a determinate quantity of thermal energy by operating between a desired maximum temperature and a controlled minimum temperature which is managed with the extraction of the thermal flows with suitable means, such as for example circulation pumps or fans, if the heat transfer flow is a gas.

Advantageously, and always in the example case of slag, the lower plates are kept at a temperature comprised in the range between about 300-350°C and about 120-275°C. A minimum temperature comprised between 150°C and 250°C is considered particularly advantageous in the case of hot water heat transfer fluid. By way of example, at the beginning of the pouring of the slag from the pot, all the lower fixed plates have a minimum operating temperature of about 150°C, while during the period in which the slag is poured, they are progressively brought to the maximum temperature of, for example, about 300°C.

According to another aspect of the present invention, the thermal extraction unit comprises circuits fluidically connected to the heat exchangers and to storage tanks of the heat transfer fluid. The circuits are provided with pumping means to move the heat transfer fluid from and toward the storage tanks and the heat exchangers, in order to carry out a recovery of energy.

According to another aspect of the present invention, the energy recovery as above can be used or directed to also produce electrical energy, for example through an energy conversion system, and/or thermal energy. In particular, although not exclusively, the apparatus of the present invention is suitable to produce thermal energy to feed one or more internal or external user machines, possibly even located at a distance, such as for example in remote heating.

According to another aspect of the present invention, the circuits described above comprise a delivery circuit and a return circuit which are fluidically connected to the heat exchangers by means of respective delivery branches at entry, and return branches at exit. At least the delivery branches can be managed independently, or in groups, by means of variable flow rate delivery pumping means. The independent management of the delivery branches allows to extract a desired thermal flow, also in relation to the cooling needs of the hot material and possibly to the needs of the user machines.

According to another aspect of the present invention, the apparatus comprises evacuation bars associated with respective fixed plates and able to be selectively driven to remove the hot material disposed on them, in order to move it downstream toward the subsequent fixed plate in a direction of transfer that goes from the inlet opening to the outlet opening. In particular, the evacuation bars are also positioned in steps alternating between the fixed plates so that after a desired and managed time during which the hot material has been stationary on the upper surface of one fixed plate, the respective evacuation bar, with a preferably rapid movement, displaces the material onto the next fixed plate.

According to one variant, while it displaces the hot material the evacuation bar is at the same time configured to scrape the surface of the fixed plate disposed below. Advantageously, each evacuation bar sweeps the entire surface of the corresponding fixed plate, or it carries out a desired and controlled scraping of such surface.

According to another variant, the evacuation bar, while it displaces the slag, mixes or turns it at the same time.

According to one variant, the evacuation bars can also be made in a cooled version, in which case they have heat exchangers with water or other heat transfer fluid connected advantageously but not necessarily to the same delivery and return circuits as the fixed plates.

According to another aspect of the present invention, each evacuation bar is mobile between a rest position in which it is covered and protected by the fixed plate above to prevent overheating, and a position of maximum extension or thrust.

According to another variant, at least some of the fixed plates and/or of the evacuation bars are vibrating.

According to another aspect of the present invention, the apparatus comprises a handling device, advantageously motorized, on which the container filled on each occasion with the hot material is positioned. This container, which in the case of slag is called pot, is disposed outside the technical volume in a raised position with respect thereto, in particular above the inlet opening which can be open-top or with controlled opening in relation to the position and inclination of the container.

According to another aspect of the present invention, the technical volume is provided with means for extracting biphasic gas/dust flows configured to perform the function of preventing the diffusion of dusts, in particular, fine ones (PM) in the internal work environment where the apparatus is installed, as well as the diffusion in the external environment, thus improving air quality. Advantageously, the extraction means cause an internal depression of the technical volume, preventing the leakage of polluting gasses and dusts.

The apparatus according to the present invention, described by way of a non limiting example in relation to the production of steel for electric furnaces and subsequent refining, can also be installed inside the building where the electric furnace is located and possibly in the vicinity of the location where the slag is tapped, in order to reduce logistics and related costs, at the same time preventing phenomena of incipient solidification of the slag.

According to one aspect of the present invention, the apparatus comprises temperature detection means disposed inside the technical volume for reading the temperature of the hot material or of the surfaces of the fixed plates.

According to another aspect of the present invention, the apparatus comprises control and command means configured to manage at least the times and frequency of intervention of the evacuation bars.

Some embodiments of the present invention concern a method for cooling a flow of the hot material as above, which has a high thermal energy and a high temperature.

The cooling of the hot material occurs through contact with the fixed plates, by making the heat transfer fluid circulate in the heat exchangers associated or integrated in the fixed plates with high thermal flows extracted through circuits fluidically which are connected to the heat exchangers and to storage tanks of the heat transfer fluid. The circuits are provided with pumping means that move the heat transfer fluid from and toward the storage tanks and the heat exchangers, in order to thermally feed one or more user machines and/or an energy conversion system in a continuous and managed manner.

According to one aspect of the present invention, the cooling of the hot material occurs through contact initially with the upper fixed plates that have a high thermal conductivity coefficient in order to achieve an at least partial vitrification of the hot material, and subsequently with the lower fixed plates that have a high thermal storage capacity in order to guarantee a thermal supply to the user machines and/or to an energy conversion system with characteristics of continuity and with extracted thermal powers managed coherently with the needs thereof.

According to another aspect of the present invention, the hot material, or material in phase transition, is disposed on the plane of each fixed plate and it remains there for a desired and advantageously managed amount of time, for example until the plate takes on the desired temperature and shape and the hot material is subsequently moved with respective evacuation bars.

Some embodiments of the present invention also concern a cooling and energy recovery plant which comprises the apparatus as above and an energy conversion device that has at least one turbine.

DESCRIPTION OF THE DRAWINGS

These and other aspects, characteristics and advantages of the present invention will become apparent from the following description of some embodiments, given as a non-restrictive example with reference to the attached drawings wherein:

- fig. 1 is a concise general view of a possible embodiment of the present invention;

- figs la and lb show some variants of a cooling and energy recovery plant according to the present invention;

- fig. 2 schematically shows an example embodiment of the invention.

We must clarify that in the present description the phraseology and terminology used, as well as the figures in the attached drawings also as described, have the sole function of better illustrating and explaining the present invention, their function being to provide a non-limiting example of the invention itself, since the scope of protection is defined by the claims.

To facilitate comprehension, the same reference numbers have been used, where possible, to identify identical common elements in the drawings. It is understood that elements and characteristics of one embodiment can be conveniently combined or incorporated into other embodiments without further clarifications.

DESCRIPTION OF AN EMBODIMENT OF THE PRESENT INVENTION

With reference to figs. 1 and 2, these show a cooling and energy recovery apparatus 100, hereafter also just apparatus 100 for simplicity.

The apparatus 100 comprises a technical volume 14, which can have any shape and composition whatsoever in relation to the contents, and is provided with an inlet opening 114 which allows access to pour a flow of hot material 13, which can be molten or semi-molten, which in the example described here is a flow of molten slag deriving from the steel production activity with an electric furnace, inside the technical volume 14 in the ways that are useful and/or necessary on each occasion. The technical volume 14 is, advantageously but not necessarily, made or lined with refractory material.

The inlet opening 114 can always remain open or be selectively closed when the hot material 13 is not introduced into the technical volume 14.

The technical volume 14 is also provided with a discharge opening 214 for the evacuation of a flow of cooled material 19, which in the example described here is a flow of at least partly vitrified slag deriving from the controlled cooling of the hot material 13.

The discharge opening 214 flows into a suitable zone in which the flow of cooled material 19 is discharged, and where continuous or discontinuous movement members 20 are reasonably present to manage it, and they are configured to prevent or in any case limit as much as possible the diffusion of dusts and allow the transfer useful for recycling.

The discharge opening 214 can be equipped with an evacuation gate 17 driven, in the useful and necessary time, by special actuator means 16, possibly governed by control and command means 18.

The technical volume 14 is also provided with means 15 for extracting biphasic gas/dust flows that are generated inside the technical volume 14. For example, the extraction means 15 can comprise one or more fans, purification, capture and/or filtering means, or even simply interception means.

The extraction means 15 cooperate with one or more suitable openings 314 present in the wall of the technical volume 14 and are driven and controlled, in suitable terms, by drive means 115, schematically shown in fig. 2.

The extraction means 15 are positioned in such a way as to generate an extraction flow which keeps the technical volume 14 in depression. For example, the extraction means 15 can be positioned near the discharge opening 214 so as to generate a conveyor current that substantially passes through the entire chamber of the technical volume 14.

The apparatus 100 can be fed by means of a pot 10 which is moved and positioned, on each occasion, by a handling device 11. Obviously, the pot 10 is disposed in an elevated position with respect to the technical volume 14 and picked up by the handling device 11 by means of suitable movement means of a known type, for example an overhead crane, not shown here.

The handling device 11 is governed by actuator means 12 managed by the control and command means 18 of the apparatus 100.

The pot 10 is positioned with respect to the inlet opening 114 according to the amount of hot material 13 present therein and to the flow of hot material 13 that is to be introduced inside the technical volume 14.

The flow of hot material 13 enters from the inlet opening 114, which can always remain open or be closed during the periods in which the hot material 13 is not introduced.

The apparatus 100 comprises a cooling and thermal recovery unit 30 configured both to cool the flow of hot material 13 and also to extract and manage the thermal flows taken from the latter.

The cooling and thermal recovery unit 30 comprises thermal extraction means 31 configured to extract the thermal energy contained in the flow of hot material 13 at least for the purposes of cooling it, and advantageously also to carry out a continuous and suitably managed thermal recovery.

The thermal extraction means 31 are positioned on respective reference planes, which in the example described here are a first, second, third and fourth reference plane PI, P2, P3 and P4.

The reference planes PI, P2, P3 and P4 are disposed at different heights and are advantageously staggered in such a way as to define a stepped configuration of the thermal extraction means 31 , which are therefore at least partly cantilevered with respect to each other.

In particular, the thermal extraction means 31 disposed on each reference plane PI, P2, P3 and P4 are positioned in such a way that the thermal extraction means 31 of a lower plane are staggered with respect to the thermal extraction means 31 of the previous upper plane, since they are at least partly overlapping each other.

The first reference plane PI is the one closest to the inlet opening 114, followed by the other reference planes P2, P3 and P4 which are gradually closer to the discharge opening 214.

According to this disposition, the cooling and thermal extraction occur according to different orders of collection, as better described below.

The thermal extraction means 31 positioned in correspondence with the first reference plane PI are substantially aligned at least partly below the inlet opening 114, so as to be the first to be intercepted by the flow of hot material 13 introduced into the technical volume 14. Furthermore, by appropriately controlling the pot 10, it is possible to regulate the flow of hot material 13 in such a way as to feed the correct quantity of material, preventing an excessive pouring which would determine an uncontrolled and unwanted spillage toward the thermal extraction means 31 of one or more of the reference planes P2, P3 and P4 below.

In one possible variant, the thermal extraction means 31 can be provided with containing barriers, possibly mobile, which allow to make the hot material 13 remain stationary on the extraction means 31 in a desired manner and for the desired amount of time.

According to the embodiment of fig. 2, the thermal extraction means 31 comprise fixed plates 40 that have the shape of a parallelepiped or other shapes deemed appropriate. The fixed plates 40, conventionally defined in the sector and hereafter in the description with the term “bars”, are advantageously made of thermo-conductive material and are provided with a respective upper surface 36 able to receive and contact the hot material 13. Preferably, the upper surface 36 is substantially flat.

The fixed bars 40, in the preferred configuration of fig. 2, are provided in two types, the first type, indicated with the reference 40a, is made of thermo-conductive material, advantageously refractory, for example silicon carbide, which has a high thermal conductivity coefficient and high abrasion resistance, the second type, indicated with the reference 40b, is made of metal material with a high melting temperature, high thermal diffusivity, high abrasion resistance and with a determinate thermal storage capacity.

With particular reference to fig. 2, the fixed bars 40a, hereafter also upper bars or fixed rapid cooling bars, are located in the initial upper part of the technical volume 14 close to the inlet opening 114, while the fixed bars 40b, hereafter also lower bars or thermal storage bars, are located after all the upper bars 40a up to the low end part of the technical volume 14 close to the discharge opening 214.

The fixed bars 40a consist of tube bundles that convey the heat transfer fluid L covered with a refractory material with conductivity greater than 20 W/mK (silicon carbide has a conductivity of 45 W/mK at 1200°C). The fixed bars 40b can have a specific thermal storage capacity greater than 300 J/kg°C.

The upper bars 40a are configured to allow a rapid solidification of the hot material 13, which in the example case of slag can arrive from the pot 10 with temperatures of about 1400°C, with energy recovery.

The lower bars 40b are configured to further cool the hot material 13 and, thanks to the high thermal storage capacity of the material that constitutes them, they are able to retain the heat in order to release it continuously during the period of time in which the flow of hot material 13 is restored with the equipping of the next pot 10.

The lower bars 40b therefore also act as a thermal accumulator or as an inertial thermal mass, in any case guaranteeing the continuity of the thermal supply.

According to some embodiments, therefore, there can be provided a group of upper bars 40a and a group of lower bars 40b in a number suitable to obtain a desired cooling curve of the hot material 13 and to allow a continuous heat extraction managed over time.

In the example case of slag, the group of upper bars 40a is configured as a whole to bring the temperature of the hot material 13 from about 1400°C to about 900°C, causing a thermal shock which advantageously causes phenomena of vitrification and volumetric stabilization of the hot material 13, while the group of lower bars 40b is configured as a whole to bring the temperature of the hot material 13 from about 900°C to about 300°C.

The fixed bars 40 are provided with respective heat exchangers 41 which can comprise a plurality of channels 44 inside which a heat transfer fluid L, for example water or other fluid, is able to flow, configured to capture the thermal energy of the hot material 13 disposed on the fixed bars 40 and convey it outside the apparatus 100, for example toward a plurality of external user machines 122 or also toward user machines inside the industrial structure which houses the apparatus 100.

The channels 44 can, for example, cross or be disposed along a longitudinal direction of development of the fixed bars 40, or according to more or less complex paths.

According to one embodiment, the upper bars 40a are provided with heat exchangers 41a advantageously located in direct contact with a lower surface thereof. The lower bars 40b are provided with heat exchangers 41b which in the example described here are made in the metal mass of the lower bar 40b; however, they can alternatively be located in direct contact with a lower surface of the latter.

In possible embodiments, each fixed bar 40 is configured to be inclinable or it can be set in vibration in order to allow the hot material 13 positioned on it to be transferred onto the fixed bar 40 below. In some embodiments, mixing means, not shown, can be provided, configured to mix the material deposited on the fixed bars 40 in order to promote the heat transfer.

The apparatus 100 also comprises evacuation bars or plates 42 configured to cooperate flush with the surface 36 of respective fixed bars 40. The evacuation bars 42 alternate with the fixed bars 40 and are present in a number equal to the number of fixed bars 40. In particular, the evacuation bar 42 is disposed above the corresponding fixed plate 40 on which it acts.

Each evacuation bar 42 can be driven independently by means of actuators 43 in order to remove the material present on the surface 36 in a desired manner, and consequently thrust it downward onto the next fixed bar 40 disposed in the immediately lower position.

The evacuation bars 42 are therefore mobile between a rest position, in which they are completely below the fixed bars 40, possibly partly or totally outside the technical volume 14, and a thrust position in which they are completely above the upper surface 36 of the fixed bar 40 disposed below. In passing from the rest position to the thrust position, the evacuation bars 42 act on the hot material 13 thrusting it downward.

The actuators 43 are connected to the control and command means 18 in order to be automatically driven according to particular operating parameters such as, for example, a determinate time interval during which the hot material 13 remains stationary on the fixed bars 40 or, for example, once a determinate temperature of the hot material 13 on the fixed bars 40 has been reached, detected by means of suitable temperature sensors, for example an infrared sensor 47; or again, once a determinate temperature of the fixed bars 40 has been reached.

In other embodiments, not shown here, the thermal extraction means 31 can be disposed in succession on a same reference plane and the evacuation bars 42 can be suitably positioned in order to move the hot material as its thermal content gradually decreases.

According to possible embodiments, the evacuation bars 42 can also have their own heat exchanger for recovering energy from the hot material 13 they move.

According to the embodiment described by way of example in fig. 2, it is provided that the flow of hot material 13 poured from the pot 10, and therefore provided with high thermal energy and high temperature, initially comes into contact with a first upper bar 40a, that is, that of the reference plane PI, and deliberately at a later time, after a certain amount of thermal energy has been extracted by means of the heat exchanger 41a of the upper bar 40a mentioned above, with a second upper bar 40a, that is, that of the reference plane P2.

Subsequently, the flow of hot material 13 is moved by the second upper bar 40a toward a first lower bar 40b, that is, that of the reference plane P3, and subsequently toward a second lower bar 40b, that is, that of the reference plane P4, there being carried out another thermal extraction by means of said lower bars 40b, through the respective heat exchangers 41b.

The displacement of the hot material 13 between one fixed bar 40 and the next can occur by activating the respective evacuation bar 42.

The cooling and thermal recovery unit 30 comprises a delivery circuit 26 and a return circuit 27 inside which the heat transfer fluid L flows. The delivery 26 and return 27 circuits are fluidically connected to the heat exchangers 41 of the fixed bars 40 by means of respective delivery branches 26a and return branches 27a, as shown by way of example in figs. 1 and 2.

The heat exchangers 41a and 41b are sized as a function of the maximum powers extracted from the hot material 13 and then sent to the user machines 122.

The delivery circuit 26 and the return circuit 27 are provided with pumping means for moving the heat transfer fluid L.

Advantageously, each delivery branch 26a and possibly, but not necessarily, also each return branch 27a can be equipped respectively with its own delivery circulation pump 21 and its own return circulation pump 22, preferably with variable flow rate, so as to be able to regulate the flow rate of heat transfer fluid L according to the amount of heat that it is necessary to extract, or that one wants to extract.

The delivery 26 and return 27 circuits are connected to one or more storage tanks 24 that feed the user machines 122 and to one or more return storage tanks 25 from the user machines 122.

The heat transfer fluid L is sent to the user machines 122 from the storage tank 24 that feeds the user machines 122 through a distribution circuit 28. The heat transfer fluid L, after having energetically fed the user machines 122, is sent to the return storage tank 25 from the user machines 122 through a return circuit 29.

The heat transfer fluid L of the delivery circuit 26 to the user machines 122 and of the return circuit 27 from the user machines 122 is moved by one or more return circulation pumps 22.

The storage tanks 24 and 25 put the delivery 26 and return 27 circuits of the recovery exchangers 41 and the feed 28 and return 29 circuits which are connected to the user machines 122 in fluidic connection.

Advantageously, the circuits 26, 27, 28, 29 and the circulation pumps 21, 22 are provided with interception members 60.

The circuits 26, 27, 28, 29 and possibly also the storage tanks 24 and 25 are equipped with temperature sensors 35, for example thermocouples, to control the temperature of the heat transfer fluid L. The temperature sensors 35 are operatively connected to the control and command means 18.

The user machines 122 connected to the apparatus 100 can be any structure, machinery or system whatsoever, such as a district heating system for example, etc., which need to be fed with a fluid with high thermal energy. A possible user machine 122 can be a plant close to the apparatus 100, or a house 122a or an inhabited area, an industrial plant 122b or other.

Possibly, a conversion system 121 can be provided suitable to receive the heat transfer fluid L converting the thermal energy into other energy, such as electrical energy.

The control and command means 18, assisted by suitable detection means, by way of example manage the process of extraction, transformation and transport of the thermal flows toward the conversion system 121, or toward the user machines 122. The apparatus 100 described here can comprise, in another embodiment, movement means 45, positioned below the last fixed bar 40, in this specific case below the lower bar 40b of the reference plane P4, in order to receive the cooled material 19 and move it toward the discharge opening 214. The movement means 45 can comprise, for example, a conveyor belt 46 with suitable characteristics.

The apparatus 100 can also comprise, in correspondence with the movement means 45, delivery means 49 provided with at least one nozzle 50 configured to deliver, toward the conveyor belt 46, a jet of liquid suitable to further cool the cooled material 19 present thereon, or to limit the dispersion of dusts before the cooled material 19 is evacuated outside the technical volume 14.

In accordance with some embodiments, there is provided a method for cooling a flow of hot material 13 that has a high thermal energy and high temperature.

The method provides to introduce the hot material 13 into the technical volume 14 through an inlet opening 114, and to make the cooled material 19, which has lower thermal energy and temperature than those of the flow of hot material 13, exit through an exit opening 214.

The method provides to bring the flow of hot material 13 into contact with the thermal extraction means 31 of the cooling and thermal recovery unit 30 inside the technical volume 14, both in order to cool the hot material 13 and also to extract at least part of the thermal energy contained therein in a continuous and managed manner, for example in relation to the thermal powers required by the user machines 122, with the ability to modulate the thermal powers in compliance with the load spectra of the same user machines 122, or according to other energy tapping criteria.

The method comprises a first step, or loading step, in which it is provided to deposit a predetermined quantity of hot material 13 onto the fixed bar 40 below the entry opening 114, that is, that of the first reference plane PI . The method also comprises a second step, or extraction step, in which it is provided to make the hot material 13 remain stationary on the fixed bar 40 of the first reference plane PI while the heat transfer fluid L is made to circulate inside the respective heat exchangers 41 in order to extract a desired quantity of thermal energy from the hot material 13. The method also comprises a third step, or transfer step, in which it is provided to move the hot material 13, from which a certain amount of thermal energy has been subtracted, from the fixed bar 40 of the reference plane PI to the fixed bar 40 of the reference plane P2, and to subsequent ones. In general, the transfer step provides a movement of the hot material 13 from one fixed bar 40 of a generic reference plane to the fixed bar 40 of the reference plane immediately downstream, in a direction of transfer that goes from the inlet opening 114 to the outlet opening 214.

The method provides to repeat the extraction step and the transfer step until the hot material 13 reaches the discharge opening 214 to be evacuated as cooled material 19 toward a collection zone outside the technical volume 14, or transferred with a continuous or discontinuous transporter to be sent for recycling.

During the extraction step, the method provides to make the heat transfer fluid L circulate inside the exchangers 41, and between the latter and the storage tanks 24, 25 through the delivery 26 and return 27 circuits, until it has extracted a desired thermal energy from the hot material 13, or it has reached a predetermined temperature.

The method provides to detect the thermal energy that each fixed bar 40 has extracted from the hot material 13 by monitoring the temperature of at least one of either the hot material 13, the fixed bar 40, for example a surface thereof, or the heat transfer fluid L that flows inside the heat exchangers 41 or in the delivery 26 and return 27 circuits.

The control and command means 18 are configured to compare the detected temperature with a predetermined temperature value and determine the drive of the evacuation bar 42 of a determinate fixed bar 40 in order to move the hot material 13 toward the next fixed bar 40. Possibly, the drive of the evacuation bar 42 is performed as a function of a predetermined amount of time during which the hot material 13 remains stationary on the fixed bar 40, which is pre-calculated in order to yield an adequate extraction of thermal energy.

In other embodiments, the control and command means 18 can command the inclination of the fixed bar 40 or make it vibrate in order to obtain the transfer of the hot material 13.

The control and command means 18 are configured to control the temperature and thermal energy status of the fixed bars 40a and of the inertial thermal masses of the fixed bars 40b, in order to manage the extraction of the thermal energies required by the user machines 122, ensuring in any case continuity of the thermal supply even in the temporary absence of hot material 13 inside the apparatus 100.

At least during the transfer and extraction steps, but preferably always when the apparatus 100 is in operation, it is provided to drive the extraction means 15 in order to evacuate and filter the fumes that are created inside the technical volume 14, keeping it in depression.

The method also provides to feed the heat transfer fluid L, advantageously after it has reached a predetermined and desired temperature, toward a plurality of user machines 122 or possibly through a conversion system 121.

It is clear that modifications and/or additions of parts may be made to the apparatus 100 and to the method as described heretofore, without departing from the field and scope of the present invention, as defined by the claims.

It is also clear that, although the present invention has been described with reference to some specific examples, a person of skill in the art shall certainly be able to achieve many other equivalent forms of cooling apparatus and method, having the characteristics as set forth in the claims and hence all coming within the field of protection defined thereby.

For example, according to some embodiments, schematically shown in figs la and lb, the apparatus 100 and the conversion device 121 can form part of a cooling and energy recovery plant 200. The conversion device 121 can comprise a turbine 121a directly connected at inlet to the return circuit 27 and at outlet to the delivery circuit 26 (fig. la), or inserted in a dedicated closed circuit which is associated with the return 27 and delivery 26 circuits by means of an exchanger 121b (fig. lb). Other components of the conversion device 121 can be a capacitor 121c, a pump 121 d or other components known per se.

In the following claims, the sole purpose of the references in brackets is to facilitate reading and they must not be considered as restrictive factors with regard to the field of protection defined by the same claims.

Claims

1. Apparatus (100) for cooling and recovering energy from a flow of molten or partly molten hot material (13) having a high thermal energy and a high temperature, said apparatus (100) comprising a technical volume (14) provided with an inlet opening (114) for introducing said hot material (13) and a discharge opening (214) for extracting a flow of cooled material ( 19) having a thermal energy lower than that of said flow of hot material (13), characterized in that said apparatus (100) also comprises a cooling and thermal recovery unit (30) disposed at least partly inside said technical volume (14) and provided with a plurality of thermal extraction means (31) configured to come into contact with said hot material (13), both in order to cool it and also to extract at least part of said thermal energy contained therein in a continuous and managed manner, and in that said thermal extraction means (31) comprise cooling fixed plates (40) which comprise at least a first group of upper fixed plates (40a) positioned close to said inlet opening (114) and which have a high thermal conductivity coefficient.

2. Apparatus (100) as in claim 1, characterized in that said thermal extraction means (31) are positioned in vertically staggered succession starting from a position below said inlet opening (114) up to a position in correspondence with said discharge opening (214).

3. Apparatus (100) as in claim 1 or 2, characterized in that said fixed plates (40) are made of thermo-conductive material and are provided with respective heat exchangers (41) inside which a heat transfer fluid (L) is flowing.

4. Apparatus (100) as in claim 3, characterized in that said fixed plates (40) comprise at least a second group of lower fixed plates (40b) having a high thermal storage capacity, located downstream of said upper fixed plates (40a) up to a low end part of said technical volume (14) close to said discharge opening (214).

5. Apparatus (100) as in claim 3 or 4, characterized in that said upper fixed plates (40a) are provided with heat exchangers (41a) located in direct contact with a lower surface thereof, and in that said lower fixed plates (40b) are provided with heat exchangers (41b) made in their own body.

6. Apparatus (100) as in claim 3, 4 or 5, characterized in that said cooling and thermal recovery unit (30) comprises circuits (26, 27) fluidically connected to said heat exchangers (41) and to storage tanks (24, 25) of said heat transfer fluid (L), and provided with pumping means (21, 22) to move said heat transfer fluid (L) from and toward said storage tanks (24, 25) and said heat exchangers (41) in order to thermally feed one or more user machines (122) and/or an energy conversion system (121) in a continuous manner.

7. Apparatus (100) as in claim 6, characterized in that said circuits comprise a delivery circuit (26) and a return circuit (27) which are fluidically connected to said heat exchangers (41) by means of respective delivery branches (26a) at entry and return branches (27a) at exit, and in that at least said delivery branches (26a) can be managed independently, or in groups, by means of variable flow delivery pumping means (21).

8. Apparatus (100) as in any claim from 3 to 7, characterized in that it comprises evacuation bars (42) associated with respective fixed plates (40) and able to be selectively driven to remove the hot material (13) disposed thereon in order to move it downstream toward the next fixed plate (40) in a direction of transfer that goes from said inlet opening (114) to said outlet opening (214).

9. Apparatus (100) as in any claim from 3 to 7, characterized in that it comprises control and command means (18) operatively connected at least to said evacuation bars (42), to systems for monitoring the temperature of said hot material (13) and/or of said fixed plates (40) and/or of said heat transfer fluid (L), and to pumps (21) for circulating said heat transfer fluid (L) in order to manage the extraction of the thermal flows from said hot material (13), ensuring continuity of supply to one or more user machines (122) and/or to an energy conversion system (121).

10. Method for cooling and recovering energy from a flow of molten or partly molten hot material (13) having a high thermal energy and a high temperature, said method providing to introduce said hot material (13) into a technical volume (14) by means of an inlet opening (114) and to make a cooled material (19) having a thermal energy and a temperature lower than that of said flow of hot material (13) exit, characterized in that said method provides to contact said flow of hot material (13) with a plurality of thermal extraction means (31) of a cooling and thermal recovery unit (30) inside said technical volume (14), both in order to cool said hot material (13) and also to extract at least part of said thermal energy contained therein in a continuous and managed manner, and in that a cooling of said hot material (13) occurs through contact with at least a first group of upper fixed plates (40a), which are part of fixed plates (40) of said thermal extraction means (31), which have a high thermal conductivity coefficient.

11. Method as in claim 10, characterized in that said cooling of said hot material (13) occurs by making a heat transfer fluid (L) circulate in heat exchangers (41 ) of said fixed plates (40) with high thermal flows extracted by means of circuits

(26, 27) that are fluidically connected to said heat exchangers (41) and to storage tanks (24, 25) of said heat transfer fluid (L) and provided with pumping means (21 , 22) to move said heat transfer fluid (L) from and toward said storage tanks (24, 25) and said heat exchangers (41) in order to thermally feed one or more user machines (122) and/or an energy conversion system (121) in a continuous and managed manner.

12. Method as in claim 11, characterized in that said cooling occurs subsequently through contact with at least a second group of lower fixed plates (40b) of said fixed plates (40) having a high thermal storage capacity in order to ensure a thermal supply to the user machines ( 122) and/or to an energy conversion system (121) with characteristics of continuity and with extracted thermal powers managed coherently with the needs thereof.

13. Method as in claim 11 , characterized in that respective evacuation bars (42) move the hot material (13) from one fixed plate (40) to the next one in a direction of transfer that goes from said inlet opening (114) to said outlet opening (214).

14. Cooling and energy recovery plant (200) comprising an apparatus (100) as in any claim from 1 to 9 and a conversion system (121) that has at least one turbine (121a).