BRPI0621950A2 - system for extracting, cooling and recovering energy from heavy ashes of a type suitable for use in combination with a combustion chamber, and method for extracting and cooling heavy ashes from a combustion chamber - Google Patents

Abstract

SYSTEM FOR EXTRACTING, COOLING AND RECOVERING ENERGY FROM HEAVY ASHS OF THE TYPE SUITABLE TO BE USED IN COMBINATION WITH A COMBUSTION CHAMBER, AND, METHOD FOR EXTRACTING AND COOLING HEAVY ASHES COMING FROM A COMBUSTION CHAMBER. The present invention relates to an air / water extraction and cooling system and energy recovery for large heavy ash flows, produced by solid fuel boilers (100), capable of reducing the final temperature of the extracted ash, without increasing the flow of air that enters the boiler throat. When the air flow required for the cooling process exceeds the maximum allowable flow in the boiler, the system allows excess air, and possible steam, to be sent to a smoke duct at the most appropriate point, thanks to a separation of the cooling environment made by the ash itself. The separation of the cooling system environments is handled automatically based on an ash temperature signal, when the system is exhausted. If the cooling air is not sufficient to cool the ash, the cooling efficiency can be increased by adding atomized water. The added water flow is dosed based generally on the ash flow and temperature, in order to guarantee the total evaporation of the injected water, in order to obtain in the exhaustion, if necessary, dry ash suitable for grinding and pneumatically transported to be mixed. to lighter ashes.

Description

"SYSTEM FOR EXTRACTING, COOLING AND RECOVERING ENERGY OF HEAVY GRAY OF A TYPE SUITABLE FOR USE IN ASSOCIATION WITH A COMBUSTION CHAMBER, AND METHOD FOR EXTRACING AND COOLING HEAVY GRAY FROM A COMBUSTION CHAMBER" Field of the invention

The present invention relates to a system and method for extracting, cooling and recovering energy from large amounts of heavy ash produced by solid fuel boilers. Fundamentals of the invention

The steady growth in demand for solid fossil fuels for power generation also makes combustion of coals and lignites with high ash content more frequent. The combustion of the latter in high power boilers involves a considerable production of heavy ashes, even 100 tons / hour, often containing high percentages of unburnt material. Dry cooling, or especially dry cooling of these quantities, requires large amounts of cooling air, even two or three times larger than high calorific fossil fuels.

As illustrated in EP 0 471.055 BI, in some known ash dry extraction and cooling systems, the cooling air, once heated due to thermal exchange with the latter, is introduced into the boiler from its bottom. Consequently, in principle, the greater the amount of ash produced, the greater the heat recovery that is supplied to the boiler by the cooling air in the manner mentioned above, both for thermal exchange with air and for combustion of unburnt material.

However, to prevent combustion efficiency from being negatively influenced by the air introduced into the combustion chamber from the bottom rather than the burners, or from other specific air inlets, and / or to avoid similar undesirable effects. In the production of nitrogen oxides (NOx), boiler designers prefer to limit this amount to a maximum of 1.0-1.5% of total combustion air.

For what has just been mentioned, known cooling systems have failed to efficiently and effectively implement dry cooling or, mainly, heavy ash dry cooling and related cooling air disposal, especially if these ashes are in large quantities with a high content of unburned material and consequently at a high temperature. In particular, even when this cooling was achieved, thermal energy recovery and disposal were achieved with considerable installation complications and the consequent very high implementation and handling costs.

Accordingly, the implicit and solved technical problem of the present invention is to provide a system and method for the extraction and cooling of heavy ash originating from a solid fuel combustion chamber which will prevent the abovementioned drawbacks with reference to the known art. Summary of the Invention

The aforementioned problem is solved by a system according to claim 1 and a method according to claim 18.

Preferred features of the present invention are present in the claims arising from the invention itself.

In particular, preferably the system has control means

"follows page 2a" fit to determine activation of water cooling depending on temperature and / or flow of heavy ash and preferably able to adjust cooling water dispensation so that it will fully vaporize during the cooling process and, in the exhaustion of said extraction and transport medium, substantially dry ashes are obtained.

According to a preferred embodiment, the system has a cooling system comprising a plurality of cooling water dispensing nozzles, preferably with means for adjusting the incoming air flow associated with at least one selected sub-group of cooling inlets. cooling air.

Preferably, the overall arrangement is such that said cooling system is capable of determining a supply of cooling air countercurrent with heavy ash flow in at least part of the extraction and transport medium.

Preferably, said cooling system comprises a plurality of cooling air inlets disposed in said extraction and transport means.

Preferably, the control means comprises temperature and / or heavy ash flow sensors arranged in the extraction and transport means and / or the pressure isolation area, whose temperature and / or heavy ash flow sensors are preferably arranged in a terminal tract of the extraction and transport means and more preferably in the discharge of heavy ash.

According to the preferred embodiment, said control means comprises load sensors arranged in the pressure isolation area.

Preferably, the system comprises means for regulating air flow and / or steam introduced into the smoke duct of the supply means arranged in the latter.

Preferably, said control means is capable of controlling the speed of at least one of the extraction and transport unit.

Preferably, the system comprises a cooling air inlet arranged immediately upstream of a crusher, the integral arrangement being such that air from such inlet is countercurrently fed with the crusher itself.

Preferably, the system comprises means for mixing heavy ashes arranged in said extraction and transport means and capable of improving the heat exchange between heavy ashes and cooling fluid, whose mixing means preferably comprises one or more preferably substantially wedge-type mixing elements. shaped like a plow.

Preferably, the extraction and transport means comprises a unit for discharging the ash out of the system.

Preferably, the system comprises means for mixing heavy ash arranged in the exhaust of the latter and capable of completing the cooling process thereof, preferably having means for feeding heavy ash cooling water whose mixing means is preferably of a continuous type.

Preferably, means for supplying cooling air and possible vapor from said mixing means to said means for supplying cooling air to the smoke duct are provided.

Preferably, the system comprises diversion means capable of selectively sending heavy ash to a discharge unit or for "following page 2c" the aforementioned mixing means.

Preferably, the method of the invention comprises a cooling phase providing flow regulation of one or more cooling air inlets arranged in the extraction and transport path.

According to a preferred embodiment, the method provides temperature and / or heavy ash flow detection performed on said extraction and transport path and / or in the pressure isolation area.

Preferably, such temperature and / or heavy ash flow detection is performed in a terminal tract of said extraction and transport path and more preferably in heavy ash exhaustion.

The method preferably also provides a load sensing performed in the pressure isolation area.

Preferably, the method provides control of the rate of extraction and / or transport of the ash along the path.

Preferably, a mixture of heavy ashes provides a cooling water supply in the ashes themselves.

Preferably, the method provides a selective shift of the heavy ash to a discharge unit or a means capable of implementing said mixing.

The present invention provides some important advantages which will be fully appreciated in light of the detailed description reported below.

The main advantage is that the present invention allows "following page 3" to perform adequate, effective and efficient dry cooling, or, mainly, dry ash cooling, without exceeding the above-mentioned limit of 1 1,5-1.5. % for cooling air introduced into the combustion chamber from its bottom. This advantage is particularly important in the case of high heavy ash coals mentioned above. This is mainly achieved by separating the total extraction and transport system in two environments with different atmospheric pressures, the first connected to the combustion chamber and the second to the economizer area. This separation, among other things, allows to send to the last area any air exceeding the above 1.5% and the possible vapor contained therein.

Based on a preferred and particularly advantageous embodiment, said separation environment is implemented by means of a transported ash head and thus substantially without the need for additional devices for the system. This enables the above mentioned effective cooling of large high temperature ash streams to be achieved while maintaining the extreme construction and simplicity of operation of the system itself, with an advantage in implementation, handling and maintenance costs. Based on this preferred embodiment, the invention allows to substantially improve the system described in EP 0 471 055 B1 by extending the potentiality of its applications to the large flows of heavy ash originating from coals or high ash lignites.

Summarizing the detailed description of the preferred embodiments reported below, the present invention relates to a large heavy ash air / water extraction and cooling system produced by solid fuel boilers capable of reducing the final temperature of the ash extracted without increasing the amount of air that enters the boiler throat, usually set by boiler designers at about 1.5% of the total combustion air. When the amount of air required for the cooling process exceeds the maximum amount that can be allowed into the boiler, the system allows excess air to be sent to the smoke duct at the most appropriate point, thanks to a separation of cooling environments made by the ash itself.

The separation of cooling system environments is automatically controlled by the system based on the flow and / or ash measurement performed on the exhaust. If cooling air is not sufficient to cool the ash, cooling efficiency can be increased by adding atomized water. The amount of water added is dosed generally based on ash flow and temperature to ensure complete evaporation of the injected water to obtain, if necessary, dry ash suitable for grinding and pneumatically transported. Water has a great advantage over air in that it allows for effective cooling of the ash itself with considerably smaller amounts by weight (around 1: 100 under the operating conditions considered here) and thus allows drastically reducing the amount of air to be sent to the smoke duct. This makes it possible to reduce the negative impact, to the point of making it practically negligible, of the fact that an increase in the amount of smoke involves the possible oversizing of the appliances and the increase in energy required to treat the smoke itself until it is flushed out of the chimney.

The proposed system, in use, consists mainly of:

1. a transition funnel between the boiler and the extractor, the latter of the type disclosed in the aforementioned EP 471,055 Bl;

2. the aforementioned puller;

3. an ash crusher;

4. a storage transition reservoir between the crusher and a conveyor-cooler, this storage reservoir being, for example, in the form of a funnel; 5. the aforementioned conveyor-cooler, equipped with appropriate plows for the purpose of mixing the ash within the conveyor itself and with the water injection nozzles;

6. a pipeline, or duct, for connection between the carrier-cooler (in the area of the latter's discharge cover) and the most appropriate point in the system to treat boiler smoke (usually upstream of the electro-filter, ie , the air / smoke changer, but whose choice could be modified depending on the composition of the smoke line, such as the presence or absence of related DeNOx and / or DeSOx systems) for cooling air output that exceeds the maximum acceptable by the boiler;

7. a final discharge apparatus capable of discharging ash by at the same time preventing uncontrolled air from entering the system (for example a valve or a vibrating extractor or simply a closed connection with another closed transportation or storage);

8. a water-ash mixer that will be activated, as an alternative to the final discharge device of the preceding item, thanks to the activation of a flow diverter, in the case of the system, if the anomalous condition of the ash (high quantities and / or temperature ) is no longer able to guarantee proper cooling of the ash - this mixer in turn will be equipped with:

- a connecting pipe, or duct, for the damp air outlet for the pipe of item 6, and

a final discharge apparatus, equivalent to that described in item 7, capable of permitting ash discharge from the system by at the same time preventing the re-entry of air from outside;

9. an adjustment and control system capable of automatically executing operations as described below in the description part of the operation.

Brief Description of the Drawings

Other advantages, features and modes of application of the present invention will be apparent from the following detailed description of some preferred embodiments shown as examples and not for limiting purposes. References will be made to the figures in the accompanying drawings, where:

Figure 1 shows a general arrangement exemplifying a preferred embodiment of the system of the invention in an operation mode providing a separation of pressures between two cooling environments;

Figure 2 shows a schematic longitudinal cross-sectional view of a separation area of the two cooling environments of the system of Figure 1;

Figure 3 shows a cross-sectional view taken along line A-A of Figure 2;

Fig. 4 shows a general arrangement exemplifying the system of Fig. 1 in a different mode of operation which does not provide for said separation in two cooling environments;

Figure 5 shows a cross-sectional view of a continuous twin-shaft mixer equipped with cooling water nozzles of the system of Figure 1 taken along line B-B of this latter figure; and

Fig. 6 shows a general arrangement exemplifying the system of Fig. 1, in an operation mode providing the still hot ash to the mixer of Fig. 5.

Detailed Description of Preferred Embodiments

Referring first to Figure 1, a system for extracting and cooling combustion residues of the type used, for example, in thermoelectric solid fossil fuel installations and according to a preferred embodiment of the invention, is designated, 1. As will be better appreciated in the following description, system 1 is particularly suitable for handling large flows of heavy ash produced by, for example, the combustion of coals or high ash lignites.

For the sake of clarity, different components of system 1 will be described hereinafter with reference to the path followed by combustion residues from their extraction from the bottom of the combustion chamber (or boiler) designated 100 for disposal. of the same.

Immediately downstream of the combustion chamber 100, or rather of a transition funnel 105 thereof, system 1 provides a first transport and / or extraction unit, in particular a dry extractor 9 made mainly of high thermal strength steel. . This extractor 9 is of the type known per se and is described, for example, in EP 0 252 967, incorporated herein by reference. Extractor 9 collects the heavy ash that precipitates downward into the combustion chamber 100 through the transition funnel 105 mentioned above.

The extractor 9, on the side walls of its own housing, has a plurality of inlet holes for the outside cooling air, distributed substantially evenly throughout the development of the extractor 9 itself, and each designated by 10. These Inputs 10 may be equipped with means for adjusting the amount or may be turned on or off. In addition, the extractor 9 has an additional inlet for the outside cooling air 19, also preferably adjusted by an automatic valve, or by equivalent flow adjustment, and arranged substantially in an end portion of the extractor 9 itself.

The cooling air is drawn through the inlets 10 and 19 of the extractor 9 and countercurrent to the conveyed ash by the effect of the depression in the combustion chamber 100. In more detail, the air enters because of the depression in the hopper. transition 105, on the bottom there is a depression adjusted by the combustion chamber control system 100 (usually around 300-500Pa under atmospheric pressure).

Downstream of the extractor 9, the ashes are supplied to a breaker or crusher 3, which crumbs its coarser fractions in order to increase the surface of the heat exchange and thus the effectiveness of the heat exchange and therefore the cooling process.

Downstream of the crusher 3 is provided an additional inlet for the external cooling air designated 17 and in this case equipped with flow adjusting means such as those already described. In this case, too, the air coming from the inlet 17 is countercurrently fed through the crusher 3 itself and along the first extractor 9 by the effect of the existing depression in the combustion chamber 100. This cooling air is usable not only to cool the ash. as well as to cool the machines.

As illustrated in greater detail in Figures 2 and 3, downstream of the crusher 3, the ashes are conveyed via a hopper / reservoir 8 to a second steel belt conveyor-cooler 6. How it will be. illustrated in more detail below, under certain conditions the described system configuration allows the hopper 8 to operate as a storage reservoir, allowing ash to accumulate to ensure disconnection of the two atmospheres from the extractor 9 and the cooler conveyor 6. In particular, in the presence of this accumulation, the conveyor 6 operates exactly like the second puller, operating continuously under a material head that ensures separation between the puller environment, associated with combustion chamber pressure 100 and one between the conveyors. / chillers associated with pressure different from economizer area. Maximum and minimum level sensors, designated 7, and a layer leveler 18, the latter arranged in an initial portion of the conveyor inlet 6, are associated with the funnel 8.

The position indicated by the layer regulator 18 associated with the conveyor cooler belt speed value 6 provides information on volumetric ash flow, applicable in conjunction with temperature measurement in order to adjust the cooling fluids.

On the conveyor 6, the ash continues to be resined both by air drawn from outside through additional inlets 11 arranged on the side walls of the extractor 6 itself in a manner similar to that already illustrated for the first extractor 9, both , when required, by accurately metered water via additional dispensing nozzles 12 positioned within the conveyor cover 6.

At this point, then, it will be understood that system 1 is equipped with an air / water cooling system implemented, among other things, by air inlets 10, 11, 17 and 19 and by water outlet nozzles 12.

System 1 provides additional means for supplying the cooling air, heated after heat exchange with combustion residues, to a smoke duct 101 associated with combustion chamber 100. In the present embodiment, this supply means comprises a duct 4, correctly insulated and thermally screened to prevent condensation, is fit for adjustment and, however, selectively blocked / enabled by means of an automatic valve 15 (or equivalent) arranged throughout its development.

In more detail, the duct 4 connects, or rather is able to connect the discharge area of the conveyor 6, and / or, in the case of the mixer 2, to said economizer area, also under negative pressure. Preferably, the duct 4 flows upstream of an air / smoke exchanger 102 (smoke side) capable of preheating combustion air and is typically provided in the combustion systems associated with the invention. This changer 102 may be of the type commonly called Ljungstrom.

The cooling ash on the conveyor 6 is made more effective by the presence of specific mixing means, in particular substantially wedge-shaped members 14, fixed relative to the conveyor belt 6 itself, and which, in the present example, are of a shape. plow. These plow members 14 are substantially evenly distributed throughout the development of the conveyor 6 and arranged in the ash transport section. As mentioned above, plow members 14 plow the ashes by operating a continuous mixture during conveyor over the belt, thereby exposing the maximum surface available for heat exchange with cooling air and / or water.

Downstream of conveyor 6 an automatic bypass valve 16 (or equivalent means for selectively diverting ash flow) is provided, which allows to selectively feed the cooled ash to the discharge medium 13, directed outward or to a continuous mixer 2 at the present example, also in communication with the outside and shown in more detail in figure 5.

Discharge conveyor 13 is equipped with a device for controlling air intake, not shown, to eliminate uncontrolled air intake from outside (or, in variations of embodiment, for connecting the system to other enclosed transport environments or storage).

Water Mixer 2 allows you to complete ash cooling, if necessary, to achieve temperature values compatible with downstream processes, or to wet ash to reduce dust emission under certain transport and disposal conditions. The mixer 2 is equipped with a discharge cover 21 equipped with means capable of discharging the ash from the system while preventing uncontrolled re-entry of outside air. Such a device may consist, for example, of a double-ended valve or rubber wipers which, when deformed under the weight of the ash, allow it to discharge into the minimum required passage section.

Based on a preferred embodiment, a pipe for connecting mixer 2 to duct 4 is provided for air and steam output at the latter.

System 1 then comprises means for sensing the temperature and / or volumetric and / or weight quantity of the ash, which, in the present example, are arranged in the terminal portion or the discharge portion of the conveyor 6 and / or on the extractor. 9 or preferably in the ash exhaust on the conveyor 13. Advantageously, sensors of the above type are also provided in the hopper / reservoir 8.

Still in this funnel 8, load cells or equivalent means may be provided to control the gray level in the funnel / reservoir.

In addition, temperature sensing means arranged in the duct 4 may be provided.

System 1 comprises a control system in communication with said sensing means capable of controlling the operating modes of system 1 in relation to ash flow and temperature.

The modes of operation of system 1, and in particular those of its cooling system, controlled by the control means described above, will now be illustrated in greater detail.

In principle, the ash flow and / or temperature values provided by the sensing means are compared by the control system to preset and stored values and, based on the result of this comparison, the mode of operation most appropriate for the operation of the system is determined. system. Regarding the need to perform temperature and / or flow measurements, it should be noted that the increase in ash temperature is generally linked to the increase in ash flow in system 1, considered herein.

The system in the initial phase is configured as shown in Figure 4 by adjusting all air inlet valves 10, 11, 17 and 9 and closing automatic valve 15 to obtain that the total amount of air that 1.5% of the combustion air is sucked through the funnel bottom throat 105 of boiler 100, counteracting ash from both extractor 9 and conveyor 6.

This operating mode is followed until the temperature of the ash in the conveyor exhaust 6 reaches the predetermined value. Tminimo · In this operating mode the control means acts on the relative speed of the extractor belt 9 and the conveyor belt 6, making substantially that the conveyor 6 has a higher potential ash flow than the extractor 9 in order to prevent the formation of a material head within the funnel 8.

When the Minimum value is exceeded, the system acts on conveyor speed 6, in particular reducing it and adjusting it to determine a buildup of ash in the funnel 8 and then creating a continuous ash plug and, in addition, opens valve 15 of duct 4 to create two different atmospheres in extractor 9 and conveyor 6 respectively, the first associated with the pressure in the boiler and the second associated with the pressure in the smoke duct.

In this operating mode, the air valve 10, 19 and 17 inlets of the extractor 9, and the funnel 8 are automatically adjusted to concentrate in the extractor only the 1.5% total cooling air that can be introduced into the boiler. Likewise the valves 11 and, in this case, subsequently, the nozzles 12 of the conveyor 6 are adjusted by first adding air to a calculated percentage so as not to influence the system in the treatment of downstream smoke and subsequently water if necessary to achieve the desired cooling.

In this room separation configuration, the cooling air acting on the main extractor 9, introduced through the inlets 10, 17 and 19, crosses this countercurrent extractor and enters the combustion chamber 100 within 1.5%. Cooling air exceeding 1.5% is collected from outside through conveyor 6 inlets 11, crosses the last in the same stream and is sucked through duct 4, along with the possible vapor produced by local water cooling, depression existing in the area of economizers.

In this way the maximum possible combustion of the possible unburned matter is obtained on the extractor belt 9 by bringing the energy back to the boiler and by adding water on the conveyor belt 6, effective cooling is obtained without requiring any consumption. greater energy by the system to treat fumes, thereby increasing the performance of the steam generator.

These operating modes are exemplified in figure 1.

In the presence of the ash head mentioned above, emptying of the hopper load 8 is prevented by controlling the speed of the conveyor 6, depending on the detections of the maximum and minimum level sensors 7. In particular, if the level reaches the minimum is provided delay until the conveyor stop 6, while when the minimum level is exceeded, the restart of the conveyor 6 is provided and upon reaching the maximum level an increase in the speed and therefore the amount of the conveyor belt 6 is provided.

In the embodiment contemplated herein, the control means may use the additional information detected by the specific sensor means relating in particular to the hopper ash temperature 8 and conveyor feed rate 6. The latter, combined with the value ( fixed section) of the extraction section exactly defines the volumetric flow of the ash. It is clarified that the level of extraction, in order to avoid possible problems in the extraction section itself, will have to be increased by an appropriate margin in size than the ash pieces coming out of the crusher 3.

In addition, in an additional operating mode exemplified in Figure 6, system 1 can also be handled in case of very high ash flows / temperatures - even higher than design values - for example, depending on fuel type or combustion chamber cleaning operations 100. In this case, when the ash temperature is considered to be above the Very high value> system 1 provides an operating mode as described above and the ash discharge is still hot to the mixer 2 instead of to conveyor 13 via bypass valve 16.

In the mixer 2, an additional water flow could be introduced to bring the ash to the provided final temperature (typically indicatively 80 ° C) with an appropriate moisture content (preferably around 10%) to ensure no dust in the operations. subsequent movements.

In order to prevent the steam generated by this cooling in mixer 2 from rising back to conveyor 6 (with the risk of generating condensate), an upside down "Y" connection can be provided directly between conveyor 6 , mixer 2 and duct 4. Thanks to this configuration, air and, in this case, steam coming from the cooler conveyor 6 goes towards the smoke line connection duct joining the steam generated in the mixer 2. The risk of condensate remains in this connecting duct (between mixer 2 and main duct 4), which could be adequately heated whenever design conditions have identified the danger of condensate formation and related ash fouling.

It will be understood that said preset temperature and / or flow values and predetermined amount of combustion air may be selectively adjusted by an operator managing system 1.

In addition, it will be understood that the previously described operating modes are just some of the possible ways to manage system 1. A simpler operating mode, for example, may provide that the gray head is created by reaching a preset temperature value, while System management, occurring for the remainder, will correctly modulate cooling air and water flows, the latter if necessary.

A number of operating modes such as those considered so far can be adjusted manually or automatically by means of a control and control system which, based on the temperature / ash flow value, determines the cooling mode of the ash itself by acting on the formation of separation area, over air - streams entering extractor 9 and conveyor 6, dosage / possible use of atomized water and activation of bypass valve.

It will generally be appreciated at this point that system 1 has full operational versatility and hence the ability to manage virtually any amount of ash, and this without any problems associated with introducing excessive cooling air flow from the bottom of boiler 100. As mentioned above, this versatility is achieved by allowing even the introduction of very high cooling air flows and by supplying the additional air flow (which is not correct to enter from the bottom of the boiler into the smoke duct) and by the possibility of adding cooling water if necessary.

In this regard, preferably system 1, with its control means, can adequately dose the amount of water used so that it vaporizes completely during the cooling process and that ashes are then obtained from conveyor 6. substantially dry, suitable for grinding and pneumatically transported. This can be achieved by keeping the final ash temperature above 100 ° C. The amount of water to be atomized and injected will be controlled by means of a thermal balance that causes heat to be removed from the ash on the one hand (amount of product for the specific enthalpy variation required between the temperature in the funnel 8 and the final discharge temperature) and on the other hand the sum of the water vaporization heat and the variation of the enthalpy submitted to the cooling air being equal.

In addition, it will be appreciated that sending part of the cooling air into the smoke duct upstream of the air / smoke exchanger allows for better heat recovery, while emphasizing the performance advantages already associated with the dry extractors used in this case. and described in the aforementioned patent EP 0 471 055 B1.

It will also be appreciated that the presence of the plow-like limbs or equivalent medium thereof, together with the possibility of selectively activating water cooling through the nozzles 12, allows to level the ash temperature.

In addition, it will be appreciated that the temperature sensors arranged in the duct 4, apart from allowing a more complete control of the system parameters, also allow to verify the formation of possible dew points throughout the duct 4 due to the steam derived from the water. cooling. In fact, knowing the temperature of the air itself and the atomized amount of water makes it easy to calculate the cooling air-related humidity and verify that:

- on the one hand, the humidity itself is below 100% with an important appropriate margin; and

- on the other hand, also that, at possible cold points in the path (and this is mainly on the conveyor cover 6 and on the surface of the connecting duct 4), the water content in the air is not such as to generate beginnings. condensate, which could result in problems for proper system operation.

In order to avoid any risk of condensate formation in the system, an additional connecting duct (or equivalent medium) may be provided between the transition funnel 105 and the conveyor 6 near the funnel 8 by selectively moving the air inlet from outside. in this duct and provide valves regulating the amount of hot air coming from the transition funnel 105 as well as the cold ambient air. This allows the system air temperature to be raised to these levels to eliminate the risk of condensate formation. The aforementioned adjustment of the inlet of hot and cold air flows could then take place based on the detections of the above mentioned temperature sensor positioned over the duct 4.

Finally, it will be understood that the aforementioned separation in two environments can also be achieved by means of devices other than those described above. For example, between the extractor 9 and the conveyor 6, additional devices such as double-ended valves or equivalent devices can again be provided for separation of the two environments by obtaining a second under the funnel / reservoir 8 crushing stage with variable quantity in relation to crusher 3, to generate in the funnel the necessary ash head able to separate the environments.

It will be appreciated that the invention allows for an effective recovery of the energy derived from sending the maximum amount of outside air over the extractor 9 and the dramatically reduced amount of air over the second extractor 6 (by the addition of water) and therefore the energy required for treatment. of the smoke.

The invention also relates to a method for extracting and recovering energy from heavy ash as described so far with reference to system 1.

The present invention has been described so far with reference to preferred embodiments. It should be understood that other embodiments belonging to the same core of the invention may exist, all within the protective scope of the claims set forth below.

Claims (34)

1. System (1) for extracting, cooling and recovering energy from heavy ash of the type suitable for use in combination with a combustion chamber, in particular for large heavy ash flows derived from, for example, solid fossil fuel in production facilities. The extraction and cooling system (1) is characterized by the fact that it comprises: (a) means (9, 6) for extracting and transporting heavy ashes from the combustion chamber (100); (b) a cooling system (10, 11, 19, 17, 12) for cooling the heavy ash arranged in said extraction and transport means (9 and 6) and capable of determining a cooling air supply in the latter; the general arrangement being such that at least part of said cooling air is introduced into the combustion chamber (100) from the bottom thereof; (c) pressure isolating means (8), capable of determining a separation of atmospheres between a first (9) and a second (6) environment of said extracting and conveying means (9, 6), said first environment ( 9) Being connected to the atmosphere of the combustion chamber. (100) and said second environment (6) being capable of being connected to the smoke duct (101); (d) control means capable of determining the activation of said ambient pressure isolation depending on temperature and / or ash flow. System (1) according to claim 1, characterized in that said cooling system (10, 11, 17, 19, 12) is of a double air-water type and said cooling water is suitable for activated in said second environment (6). System (1) according to any one of the preceding claims, characterized in that the general arrangement is such that under the condition of pressure separation from environments (9, 6), said cooling system (10, 11, 17 , 19, 12) is able to determine a supply of cooling air countercurrent with the heavy ash flow in said first environment (9) and of the same current with such flow in said second environment (6). System (1) according to any one of the preceding claims, characterized in that said control means is capable of determining said room separation (9, 6) so that cooling air flow entering the chamber of combustion (100) from the bottom does not exceed a predetermined amount of the total combustion air. System (1) according to the preceding claim, characterized in that said predetermined quantity is approximately 1.0-1.5%. System (1) according to any one of the preceding claims, characterized in that it comprises means (4) for supplying cooling air and the possible vapor derived from the cooling water into a combustion smoke duct (101). associated with the combustion chamber (100) and wherein said means (4) for supplying the smoke duct (101) is capable of connecting the latter to said second environment (6) substantially downstream of the cooling process. System (1) according to claim 6, characterized in that said means (4) for supplying cooling air to the smoke duct (101) reaches said smoke duct in the economizer area. System (1) according to Claim 6 or 7, characterized in that said means (4) for supplying cooling air to the smoke duct (101) exits upstream of a suitable air / smoke exchanger (102). to preheat the combustion air. System (1) according to any one of claims -6 to 8, characterized in that said pressure isolating means comprises means (15) for interdicting / enabling said means (4) for supplying the smoke duct ( 101), controlled by said control means to determine said separation environments (9, 6) when necessary. System (1) according to any one of the preceding claims, characterized in that said extraction and transport means comprise a first extraction unit (9) arranged, or suitable for being arranged, immediately downstream of the combustion chamber ( 100), and a second transport unit (6) arranged downstream of said first unit (9) and wherein said pressure isolating means (8) are capable of producing a pressure separation between said first (9) and second (6) extraction and transportation units. System (1) according to any one of the preceding claims, characterized in that said pressure isolating means (8) comprises means capable of creating a heavy ash head between said two environments (9, 6), capable of to determine said pressure separation of these. System (1) according to the preceding claim, characterized in that said pressure isolating means comprises a storage reservoir means (8) capable of receiving the heavy ashes creating said head. System (1) according to the preceding claim, characterized in that said pressure isolating means comprises a funnel (8) capable of receiving heavy ashes creating said head. System (1) according to any one of claims 11 to 13, characterized in that said control means comprises one or more level sensors (7) arranged on said head. System (1) according to any one of the preceding claims, characterized in that it comprises a heavy ash crusher (3) arranged in said extraction and transport means (6, 9, 13), whose crusher (3) It is brought between said first (9) and second (6) environments. System (1) according to claim 15 and according to any one of claims 7 to 19, characterized in that said means, capable of creating an isolation head (8), is capable of determining the formation of said one. head immediately downstream of said crusher (3). System (1) according to any one of the preceding claims, characterized in that it comprises a duct for supplying hot air from said combustion chamber (100, 105) to the unit (6) of said extraction means and contained in said second environment. 18. Method for extracting and cooling heavy ash from a combustion chamber, in particular for large flows of heavy ash derived from, for example, fossil fuel in an energy production system, comprising the steps of: ( (a) extract heavy ashes from the combustion chamber (100, 105); (b) cool these heavy ashes along an extraction and transport path (9, 6, 13) by supplying cooling air along the latter, introducing at least downstream of said air into the chamber downstream of the cooling process. combustion (100, 105) from the bottom thereof; (c) depending on the temperature and / or flow of the heavy ash, selectively activate a pressure isolation between a first (9) and a second (6) environment arranged along said extraction and transport path, said first environment (9). ) being arranged immediately downstream of the combustion chamber (100, 105) and said second environment (6) being arranged downstream of said first environment (6). Method according to claim 18, characterized in that said cooling phase (b) is of the double air-water type and said phase (b) provides for activation of water cooling depending on the temperature and / or amount of water. Heavy ashes. Method according to claim 18 or 19, characterized in that said step (b) provides a dispensing and cooling water adjustment such that it vaporizes completely during the cooling process and that upon exhaustion of said cooling path. extraction and transport (9, 6, 13) substantially dry ashes are obtained. A method according to any one of claims 18 to 20, characterized in that said step (b) provides a water cooling activation in said second environment (6). Method according to any one of claims 18 to 21, characterized in that said cooling phase (b) provides, under said pressure separation condition of the environments (9, 6), a supply of cooling air in countercurrent with the flow of heavy ash in said first environment (9) and of the same current with this flow in said second environment (6). A method according to any one of claims 18 to 22, characterized in that said step (c) provides that said room separation (9, 6) is performed so that cooling-flow air entering the combustion chamber (100) from the bottom does not exceed a predetermined amount of total combustion air. Method according to the preceding claim, characterized in that said predetermined amount is approximately 1.0-1.5%. Method according to any one of claims 18 to 24, characterized in that it provides a supply of cooling air and possible vapor derived from the cooling water to the combustion smoke duct (101) associated with the combustion chamber ( 100), wherein said supply to the smoke duct (101) occurs starting from said second environment (6), substantially downstream of the cooling process. Method according to claim 25, characterized in that said supply (4) to the smoke duct (101) provides an outlet in the latter in the area of the economizers. Method according to Claim 25 or 26, characterized in that said supply to the smoke duct (101) provides an outlet in the latter, upstream of an air / smoke exchanger (102), capable of preheating the smoke. combustion air. Method according to any one of claims 25 to 27, characterized in that said step (c) provides that said pressure isolation is obtained by interdicting / enabling said cooling air supply to the smoke duct. A method according to any one of claims 18 to 28, characterized in that said extraction and transport path comprises a first extraction portion (9) arranged immediately downstream of the combustion chamber (100) and a second transport portion. (6) arranged downstream of said first portion (9), and wherein said step (c) provides that said pressure isolation is obtained between said first (9) and second (6) extraction and transport portions. A method according to any one of claims 18 to 29, characterized in that said step (c) provides for the creation of a heavy ash head between said two environments (9, 6), capable of determining said separation of pressure of these. Method according to the preceding claim, characterized in that said step (c) provides level detection of said head. Method according to any one of claims 18 to 30, characterized in that it provides a heavy ash crushing performed within said extraction and transport path (6, 9, 13). A method according to the preceding claim, characterized in that said crushing is performed between said first (9) and second (6) environments. Method according to any one of claims 18 to 33, characterized in that it provides a supply of hot air from the combustion chamber (100, 105) to a portion (6) of said extraction and transport path contained in the mentioned second environment.