EA038810B1 - Fluidized bed boiler assembly and method of burning at least two types of fuel in a fluidized bed boiler - Google Patents

Abstract

Described is a fluidized bed boiler assembly comprising a fluidized bed boiler comprising a combustion chamber, a first conveyor (5) for feeding a first fuel mixture to the fluidized bed boiler (1) and/or for introducing the fuel mixture into the combustion chamber, a first fuel feeder (12) and a second fuel feeder (13), the first outlet of the first feeder (12) and the first outlet of the second feeder (13) opening onto or into the first conveyor (5) side by side or with each other. Also described is a method of simultaneously combusting at least two types of fuel in a fluidized bed boiler (1).

Description

Field of the invention

The invention relates to a fluidized bed boiler system, which comprises a fluidized bed heating boiler, comprising a combustion chamber, a first conveyor for supplying a fuel mixture to a combustion chamber, a first fuel feeder and a second fuel feeder, the first outlet of the first feeder and the first outlet of the second feeder being opened onto or inside the first conveyor. In addition, the invention relates to a method for combusting a plurality of types of fuels with different combustion characteristics in a fluidized bed boiler.

Background of the invention

Fluidized bed boilers are known in the art, i. E. boilers where combustion takes place in a fluidized bed. Fluidized bed boilers can be used to burn various types of fuels, however, nowadays, fluidized bed boilers are almost always used to burn the same type of fuel. And if it is necessary to burn another fuel, then the original fuel is replaced with another.

Fuels that can be used for combustion in a fluidized bed differ, for example, in the following characteristics: calorific value, calorific value, water content, ash content, volatile fuel content, C, H, S, N and O content, Cl and F content , bulk density, angle of repose, specific gravity, particle size and other characteristics. On the basis of at least some of the above characteristics, the design and control of the boiler operation are proposed, in particular to achieve maximum efficiency while maintaining the longest boiler life or keeping the minimum duration of the boiler outage. Different types of fuels require different amounts of air to burn properly because each fuel has a different flammable content.

In the process of substoichiometric combustion, the fluidized bed contains excess fuel and has a lower oxygen content than would be required for complete combustion of the fuel. If the oxygen content of the fluidized bed were to increase, there would be a rapid increase in temperature due to the combustion of excess fuel, and the fluidized bed would quickly become clogged, and therefore it would be necessary to shut down the operation of the fluidized bed boiler.

For this reason, it is always necessary to calculate in advance the technological parameters for a specific boiler and a specific fuel, and the calculation results are simultaneously influenced by the design and size of the boiler, the type of fuel, in particular the content of oxygen, carbon, sulfur, nitrogen, hydrogen and, if appropriate, other substances, as well as the characteristics of the fuel and the melting point of ash.

Based on the above calculations, the oxygen content in the fluidized bed is adjusted for a specific fluidized bed boiler, a specific fuel, i.e. the specific characteristics of the composition of combustible substances in the fuel, as well as for the specific ratio of air and recirculated flue gases supplied as a fluidizing medium to the fluidized bed.

The fuel is fed to the fluidized bed boiler using a hopper or conveyor and then a chute. In some cases, to improve the distribution of the fuel over the surface of the fluidized bed, a carrier gas is added to increase the momentum of the fuel. The carrier gas is usually secondary air. The spread of the fuel (through a single chute) is limited to a certain size of the bed area. Depending on the type of the fluidized bed boiler, the size of the area of the fluidized bed, as well as the type of fuel and its properties, the number of chutes through which the fuel enters the combustion chamber is selected, i.e. into the fluidized bed.

When trying to burn several types of fuels with different fuel characteristics and combustion characteristics, technological problems arise due to the inhomogeneity of the fuel in the space of the fluidized bed, in particular in boilers having an increased size or an increased area of the fluidized bed. Essentially, when several types of fuel are supplied by two or more feeding devices into a common hopper, segregation of each type of fuel occurs in the boiler hopper, in particular in the case of fuels with different characteristics. The more the fuel characteristics differ, the greater the degree of segregation of the individual fuel type and, consequently, the flow to another part of the fluidized bed, and / or due to different values of the bulk density of the fuel there is a periodic interruption of the flow of one fuel by the flow of another fuel with the formation of a fluidized bed region in which for example, the first fuel is missing, whereby the boiler control parameters calculated for the fuel mixture will not correspond to such a local fuel mixture / sole fuel composition.

As mentioned above, the types of fuels differ in their characteristics, including, in particular, the required amount of supplied oxygen and the critical ash melting temperature, and their differences can be taken into account when regulating the boiler, in particular when regulating the oxygen content and the temperature of the fluidizing medium and, possibly, secondary air / gas. These characteristics are taken into account for the mixture as a whole, and not for any local inhomogeneity of the fuel mixture in the fluidized bed. Thus, in particular, local fusion of the fluidized bed occurs, in particular, in those regions where fuel is supplied to the fluidized bed instead of the expected fuel mixture, or the resulting fuel mixture does not correspond to the average composition of the supplied fuel mixture.

These problems are even more pronounced when each type of fuel is fed through a separate hopper or separate conveyor, where, despite attempts to blow or inject each type of fuel supplied by each hopper or each conveyor, throughout the fluidized bed.

Although these problems are known, to date there have been no reports of the proposed stirring of the fuel prior to its introduction into the fluidized bed boiler. If a mixer were intended for this purpose, it would have to be an independent device that would be expensive (to manufacture and operate) and take up a lot of space, and, secondly, there would be a loss of time for sufficiently thorough mixing of the fuel mixture. to obtain a fuel mixture.

As indicated above, in substoichiometric combustion, the fluidized bed contains an excess of fuel and also has a lower oxygen content than would be required for complete combustion of the fuel. Fuel burns imperfectly, i.e. its most abundant component (carbon) burns to CO. If the oxygen content in the fluidized bed was increased, the fuel would be burned due to the combustion of excess fuel to CO2, thus increasing the calorific value of the fuel (from about 30 to 100%, i.e. from 10.3 to 33.8 MJ / kg) , which corresponds to a threefold increase in the generated heat and leads to a rapid increase in temperature and to a rapid clogging of the fluidized bed with the need for subsequent suspension of the operation of the fluidized bed boiler. As such, when the air content is increased by 10%, the heat generation is increased by 30%. This leads to an imbalance in the heat balance in the fluidized bed and to a rapid increase in temperature in the fluidized bed. As described herein, different types of fuels require different amounts of oxygen to burn; thus, the uneven fuel supply is the reason why it is impossible to simply burn multiple types of fuels at the same time or continuously or staggered fuel ratios without adversely changing the temperature in the fluidized bed and risking the operation of the fluidized bed boiler.

Thus, an object of the present invention is to allow the combustion of several types of fuels with different combustion characteristics and to regulate the fluidized bed boiler so as not to be damaged by plugging. A further object of the present invention is to provide control of combustion in a fluidized bed boiler and switching from one fuel mixture to another.

In addition, some types of fuels, such as sludge, agricultural biomass and segregated municipal waste, may contain significant amounts of chlorine, typically up to 1% and in the range from 0.2 to 0.5 % Cl calculated on dry matter. Fuel of the indicated types for the boiler is a real risk of corrosion, in particular high temperature chlorine corrosion (HCl) and chloride corrosion (chloride salts). Corrosion of both of these types affects the heat exchange surfaces of the boiler, in particular on surfaces that are in conditions of no or insufficient cooling, such as lining, thermal cyclones, curtains, curtains, plug-in burners (which are not air or steam cooled), as well as superheaters and grill fluid nozzles.

Cold surfaces are threatened by low temperature chlorine corrosion caused by acidic components of flue gas condensate, in particular HCl and SO2. To prevent this risk, calculations are made for the operation of the boiler, in particular for regulating the temperatures in the fluidized bed and above the fluidized bed, as well as the temperatures of the flue gases used to produce the heated water / superheated water / steam in the system. These calculations should take into account the expected Cl content of the fuel mixture and, if significant, the temperature of the flue gas supplied to the heat exchangers should be adjusted so as to reduce the risk of corrosion. However, if local inhomogeneities of the fuel mixture occur in the fluidized bed, the calculated values of temperature and oxygen content may be insufficient to prevent / sufficiently reduce the aforementioned corrosion, since the chlorine content is not compensated by calcium binding from the introduced CaCO ₃ at some points in the fluidized bed, and, in in general, the content and temperature of the fluidizing medium or secondary air do not take on appropriate values in some areas or at some points in time.

In particular, if the fuel obtained from the separated municipal waste (RDF) or sewage sludge was burned in boilers, it was burned in boilers that had a relatively low steam temperature of up to 400 ° C, in exceptional cases up to 420 ° C. In this case, the pressure is usually

- 2,038810 was up to 40 bar and the inlet water temperature was 105 ° C. This is because at elevated steam temperatures, the superheaters were exposed to high temperature chlorine and chloride corrosion, and then the end heat exchangers (Luwa) were exposed to low temperature chlorine corrosion. Corrosion of these types also affected the boiler lining. Inconel material was used for superheaters and final heat exchangers to reduce corrosion. The corrosion of these materials decreased and the service life under corrosion conditions increased, but at the expense of the disproportionately high price of the boiler. However, the use of Inconel-type materials did not prevent the deposition of low-melting chlorides (KCl, NaCl, CaCl ₂ ) with the formation of glassy deposits on the boiler surfaces with zero or insufficient cooling. It is under the glassy sediments that salts act that destroy materials. When alkali metals come into contact with chlorine, chlorides are formed, and the ash melting point is 801 ° C for NaCl, 768 ° C for KCl and 782 ° C for CaCl ₂ ; Certain heavy metal chloride salts, in particular Cd, Cu, Pb and Zn, also have similar melting points, which, during longer storage times at temperatures usually exceeding 800 ° C, combine with chlorine to form heavy metal chloride salts. The effect of the chlorides of these heavy metals is the same as in the case of KCl, NaCl and CaCl ₂ ; As they flow out of the flue gas, they are deposited mainly on superheater boilers, where they cause chloride corrosion, which gradually destroys even very expensive materials such as Inconel. The vitreous deposits grow and create crusts that gradually glue all the heat exchangers to such an extent that it becomes necessary to shut down the operation of the boiler, and its cleaning is difficult. Reduction of high temperature corrosion can be prevented by adding limestone to the fuel of the fluidized bed boiler, where the limestone binds organic chlorine to form CaCl ₂ . Those. salts are formed which, like KCl and NaCl, cause chloride corrosion, which is more dangerous than high-temperature chlorine corrosion because it also produces irreparable or unsatisfactory deposits in addition to corrosion.

The so-called chlorine removal method is sometimes used to remove chloride salt deposits, and this method uses an ammonium sulfate solution according to the equations below, where the chlorides are converted to hydrogen chloride (HCl), which is less hazardous than chloride salts (NH ₄ ) ₂ SO ₄ 2NH ₃ + SO ₃ + H ₂ O

2KS1 + SO3 + H ₂ O K ₂ SO ₄ + 2HC1

This method reduces the amount of deposits by about 50%, but from a practical point of view it turns out to be useless. If even a thin layer of deposits forms, corrosion will still occur. Thus, this method excessively increases operating costs. The introduction of ammonium sulfate is used in a manner similar to selective non-catalytic NOx reduction.

A further object of the present invention is to provide controlled combustion in a fluidized bed boiler in such a way that it can be configured to eliminate the formation of chlorine and chloride corrosion on heat exchangers that are heated by flue gases and on fluidized bed nozzles (so-called Luwa).

Brief disclosure of the technique of the invention

The above objects and some other problems are solved by the proposal of a fluidized bed boiler system and combustion method, which are defined in the claims of the present invention.

In particular, the above-mentioned disadvantages of the prior art are largely eliminated by the fluidized bed boiler system according to the present invention, the above-mentioned system comprising a fluidized bed boiler having a combustion chamber;

a first conveyor for supplying a fuel mixture to a fluidized bed heating boiler and / or for loading a fuel mixture into a combustion chamber;

a first fuel feeder and a second fuel feeder, wherein the first outlet of the first feeder and the first outlet of the second feeder open to the surface or inside of the first conveyor, and wherein the aforementioned outlets are located in close proximity or distance from each other.

Advantageously, the first outlet of the first feeder and the first outlet of the second feeder open to the surface or inside of the first conveyor, the openings of the above outlets being located in close proximity or spaced from each other to allow the fuel supplied by the second feeder to be stacked on the fuel supplied by the first feeder, and / or the system further comprises a first fuel hopper, the outlet of which is connected to the inlet of the first fuel feeder, and a second storage bin, the outlet of which is connected to the inlet of the second fuel feeder.

Advantageously, the system comprises a first fuel hopper, the outlet of which is connected to the inlet of the first fuel feeder, and a second storage hopper, the outlet of which is connected to

- 3 038810 inlet of the second fuel feeder.

According to a further advantageous embodiment, the system comprises a storage tank for CaCO ₃ and / or a storage tank containing inert material for the fluidized bed, and the outlets of the aforementioned storage tanks that open to the surface or inside of the first conveyor are located at a distance from the outlets of the first and / or second feeders.

According to another advantageous embodiment, the system further comprises a second conveyor for loading the fuel mixture into the combustion chamber in an area located at a certain distance from the area where the mixture supplied by the first conveyor is loaded, wherein the second outlet of the first feeder and the second outlet of the second feeder open to the surface or inward of the aforementioned the second conveyor, and these outlets are located in close proximity or at a distance from each other.

According to a further advantageous embodiment, the system further comprises a third fuel hopper, the outlet of which is connected to the inlet of the third fuel feeder, the first outlet of the aforementioned feeder opening to the surface or inside of the first conveyor, and a fourth fuel bin, the outlet of which is connected to the inlet of the fourth fuel feeder, the first the outlet of the last feeder also opens to the surface or inside of the first conveyor, and the first outlets of the aforementioned feeders have corresponding openings located in the immediate vicinity or at a distance from each other on the surface or inside the first conveyor.

Advantageously, the system further comprises a first chute opening into a combustion chamber of the fluidized bed heating boiler, the inlet of the aforementioned first chute being connected to the outlet of the first conveyor. In addition, advantageously, the system further comprises a second chute opening into a combustion chamber of a fluidized bed heating boiler, the inlet of the aforementioned second chute being connected to the outlet of the second conveyor, and wherein the outlets of the first and second chutes are spaced apart from each other in a horizontal projection.

According to a further advantageous embodiment, the system further comprises a first feed turnstile for loading the fuel mixture supplied by the first conveyor to the first chute, and a second feed turnstile for loading the fuel mixture supplied by the second conveyor to the second chute.

According to a particularly advantageous embodiment, the first conveyor and / or the second conveyor is a worm conveyor and / or a chain conveyor and / or a belt conveyor and / or a link conveyor.

The system may further comprise a feed duct for a fluidizing medium, the aforementioned feed duct opening into fluidizing inlets of a combustion chamber of a fluidized bed heating boiler, and at least one feed duct for secondary air or secondary gas.

Advantageously, the fluidized bed heat boiler system further comprises a first heat exchange device, in which the flue gas outlet is connected to the flue gas outlet of the fluidized bed heat boiler and comprises at least one heat exchanger for heating water and / or for heating a mixture of steam and water, and / or for heating the steam by means of flue gases discharged from the fluidized bed heating boiler and conducted over the surface of at least one of the aforementioned heat exchangers.

Advantageously, such a fluidized bed heat boiler system further comprises a second heat exchanger, in which the flue gas outlet is connected to the flue gas outlet of the first heat exchanger, the aforementioned second heat exchanger comprising a heat exchanger for preheating the water, the outlet of the aforementioned heat exchanger optionally connected to the heater, and / or a heat exchanger for heating the recirculated flue gases, the inlet of the aforementioned heat exchanger may be connected to the flue gas outlet of the second heat exchanger, and its outlet may be connected to at least one aforementioned duct for supplying the fluidized bed boiler with secondary air or secondary gas, and / or a heat exchanger for heating the recirculated flue gases, wherein the inlet of the aforementioned heat exchanger can be connected to the flue gas outlet of the second heat exchanger and its outlet sc can be connected to the aforementioned fluidizing inlets, and / or a heat exchanger for heating the secondary air, the outlet of the aforementioned heat exchanger being connected to at least one duct for feeding a fluidized bed heat boiler with secondary air, and / or a heat exchanger for heating the primary air, wherein the outlet of the aforementioned heat exchanger may be connected to the aforementioned fluidizing inlets.

Advantageously, a fluidized bed heat boiler system according to the present ISO 4 038810 comprises a second heat exchanger, in which the flue gas outlet can be connected to the flue gas outlet of the first heat exchanger, the aforementioned second heat exchanger comprising a heat exchanger for heating secondary air, the outlet of the aforementioned the heat exchanger can be connected to at least one channel for supplying a heating boiler with a fluidized bed with secondary air, a heat exchanger for heating the primary air, and the outlet of the aforementioned heat exchanger can be connected to the aforementioned fluidizing inlets, and the heat exchanger for heating the secondary air is located, in relation to towards the direction of flow of flue gases in the second device, upstream of the heat exchanger for heating the primary air.

According to a particularly advantageous embodiment, the system of a thermal fluidized bed boiler comprises a control unit adapted, on the basis of the ratio of the outputs of the heat exchangers contained in the second device, to adjust the ratio of air and recirculated flue gases in the fluidizing medium supplied to the fluidizing inlets in such a way that the temperature of the fluidizing medium passed through the fluidizing inlets is less than 250 ° C, preferably less than 220 ° C, more preferably less than 200 ° C, even more preferably less than 180 ° C, even more preferably less than 160 ° C, even more preferably less than 140 ° C, even more preferably less than 120 ° C and most preferably less than 100 ° C, and / or such that the temperature of the flue gases above the fluidized bed is less than 890 ° C, preferably less than 850 ° C, more preferably less than 800 ° C, even more preferably less than 780 ° C and most preferred significantly less than 750 ° C, and / or configured to regulate the supply of secondary gas that enters the fluidized bed boiler and contains secondary air or a mixture of air and recirculated flue gases discharged from the fluidized bed boiler, so that the temperature of the flue gases downstream of the first and / or each possible subsequent secondary gas inlet is less than 980 ° C, preferably less than 950 ° C, more preferably less than 920 ° C, even more preferably less than 890 ° C, even more preferably less than 860 ° C and most preferably less than 800 ° C, and / or such that the temperature of the flue gases inside the first heat exchanger, in particular in the area where the flue gases are conducted to the surfaces of the heat exchanger located in the immediate vicinity of the flue gas inlet and / or to the surfaces of a heat exchanger located in the immediate vicinity of the flue gas inlet and perpendicular to the direction of flow of the flue gases is less than 850 ° C, preferably less than 830 ° C, more preferably less than 780 ° C, even more preferably less than 750 ° C, even more preferably less than 700 ° C, even more preferably less than 680 ° C, even more preferably less than 650 ° C and most preferably less than 620 ° C.

In this regard, it is advantageous if the system further comprises a heat exchanger for heating the recirculated flue gases added to the primary air, and the inlet of the aforementioned heat exchanger can be connected to the flue gas outlet of the second heat exchanger, and its outlet can be connected to fluidizing inlets, and when the aforementioned heat exchanger is located with respect to the flow direction of the flue gases in the second device upstream of the heat exchanger for heating the secondary air.

It also turns out to be advantageous if the system further comprises a heat exchanger for heating the recirculated flue gases, wherein the inlet of the aforementioned heat exchanger can be connected to the flue gas outlet of the second heat exchanger, and its outlet can be connected to at least one inlet for feeding the secondary fluidized bed boiler. gas or secondary air, and wherein the aforementioned heat exchanger is located with respect to the direction of flow of flue gases in the second device upstream of the first heat exchanger for heating the recirculated flue gases (if present) or upstream of the heat exchanger for heating the secondary air.

In addition, it is also advantageous if the system further comprises a heat exchanger for preheating the water, said heat exchanger being located upstream of the aforementioned heat exchangers in the second heat exchanger with respect to the direction of flow of the flue gases.

The aforementioned drawbacks of the prior art are also largely eliminated by a method for the simultaneous combustion of at least two types of fuel in a fluidized-bed heating boiler, in which a fluidizing medium is blown from below into a fluidized-bed heating boiler, wherein the first fuel is supplied by the first feeder to the surface or to the interior of the first conveyor, transported by the first conveyor into a fluidized-bed thermal boiler, and then loaded into the combustion chamber of a fluidized-bed thermal boiler, and the second fuel is supplied by the second feeder to the surface or inside of the first conveyor, and the area for supplying the first fuel is located next to the area for supplying the second fuel or at a distance from it, and when

- 5,038810 the second fuel is stacked on the first fuel, transported by the first conveyor to the fluidized bed heating boiler, and then loaded together with the first fuel into the combustion chamber of the fluidized bed heating boiler.

In general, the method consists in placing the second fuel on top of the first fuel, and in the case where the conveyor is a chain conveyor, belt conveyor or link conveyor, such a fuel mixture containing two stacked layers of different types of fuel in a given ratio, loaded into the combustion chamber (directly or through a chute). In the case where a worm conveyor is used, the different types of fuel are mixed while passing through the conveyor, but the predetermined mutual ratio of the different types of fuel introduced into the combustion chamber remains unchanged. In the claimed structural configuration, the fluidized-bed thermal boiler system is also configured to stack the second fuel on the first fuel or supply the second fuel to the first storage hopper.

The fuels of the above types are advantageously selected from the group consisting of fuels obtained from segregated municipal waste, preferably granular fuels, lignite, coal, petroleum coke, wood chips, wood-based pellets, coconut shells, agricultural pellets or briquettes biomass, fuels obtained from sludge from water treatment plants, fuels obtained from the processing of food products, forage plants and biomass, fuels obtained from agricultural waste, fuels obtained from waste oils or grain alcohols, in particular from bottoms, or fuel obtained from lignin, bran, straw straw or agricultural manure.

As mentioned above, one of the usable types of fuel can be a fuel obtained from separated municipal waste, preferably a fuel in granular form and supplied in an amount corresponding to at least 50 wt.%, Preferably at least 70 wt.% preferably at least 80 wt%, preferably at least 90 wt%, based on the total amount of fuel supplied to the combustion chamber of the fluidized bed thermal boiler.

It also turns out to be advantageous if the fluidizing medium is blown into the fluidized bed boiler through the respective inlets, and if the secondary gas is blown into the fluidized bed boiler at at least one height level above the level of the fluidizing medium inlets, preferably at least two different height levels, preferably at least two different height levels.

Advantageously, the secondary gas is blown into the fluidized bed boiler at at least two height levels above the fluidized bed, and the part of the secondary gas supplied at one level differs in composition and / or temperature from the part supplied at the other level.

The flue gases discharged from the fluidized-bed heating boiler can advantageously be conducted into a first heat exchanger comprising at least one heat exchanger for heating water and / or for heating a mixture of steam and water and / or for heating steam by means of flue gases, discharged from a thermal fluidized bed boiler, after which the aforementioned flue gases are conducted into a second heat exchanger, in which the flue gases flow over the surface of at least one heat exchanger for heating the secondary air, and then over the surface of at least one heat exchanger for heating the primary air, wherein the air heated in the heat exchanger for heating the primary air is supplied to the fluidizing inlets of the fluidized bed heating boiler, and the air heated in the heat exchanger for heating the secondary air is supplied to the fluidized bed heating boiler at at least one level corresponding to the supply level secondary hot gas into a fluidized bed heating boiler.

Advantageously, the flue gases are passed over the surface of the heat exchanger to preheat the recirculated flue gases added to the fluidizing medium before being passed over the surface of the heat exchanger to heat the secondary air in the second heat exchanger, wherein the recirculated flue gases are fed to the fluidizing inlets of the fluidized bed heating boiler after preheating to the first heat exchanger.

It also turns out to be advantageous if flue gases flow over the surface of the heat exchanger to heat the recirculated flue gases added to the secondary gas, before being fed to the surface of the heat exchanger for preheating the recirculating flue gases added to the fluidizing medium (if present) or before being fed to the surface of the heat exchanger. for heating the secondary air, the flue gases being passed through the filter after passing through the second heat exchanger, after which part of the flue gases are fed to the heat exchanger for heating the recirculated flue gases added to the secondary gas, the last heat exchanger supplying the flue gases to at least one inlet for supplying secondary gas to a fluidized bed boiler.

According to a particularly advantageous embodiment, the temperature of the fluidizing

- 6,038810 of the medium supplied through the fluidizing inlets is controlled based on the ratio of the recirculated flue gases and the air in the fluidizing medium supplied to the fluidizing inlets and based on the ratio of heat powers in the second heat exchanger, so that the above-mentioned temperature is less than 250 ° C, preferably less than 220 ° C, more preferably less than 200 ° C, even more preferably less than 180 ° C, even more preferably less than 160 ° C, even more preferably less than 140 ° C, even more preferably less than 120 ° C, and most preferably less than 100 ° C, and / or such that the temperature of the flue gases above the fluidized bed is less than 890 ° C, preferably less than 850 ° C, more preferably less than 800 ° C, even more preferably less than 780 ° C and most preferably less than 750 ° C, and / or the supply of secondary gas that enters the fluidized bed boiler and contains secondary air or a mixture in the air and recirculated flue gases discharged from the fluidized bed boiler are controlled such that the flue gas temperature downstream of the first and / or each possible subsequent secondary gas inlet is less than 980 ° C, preferably less than 950 ° C, more preferably less than 920 ° C, even more preferably less than 890 ° C, even more preferably less than 860 ° C and most preferably less than 800 ° C, and / or the secondary gas supply is controlled such that the temperature of the flue gases inside the first heat exchanger, in particular in the area where the flue gases are conducted to the surfaces of a heat exchanger located in the immediate vicinity of the flue gas inlet and / or to the surfaces of a heat exchanger located in the immediate vicinity of the flue gas inlet and perpendicular to the direction of flow of the flue gases is less than 850 ° C, preferably less than 830 ° C, more preferably less than m 780 ° C, even more preferably less than 750 ° C, even more preferably less than 700 ° C, even more preferably less than 680 ° C, even more preferably less than 650 ° C and most preferably less than 620 ° C.

Advantageously, the flue gases are conducted into a first heat exchanger after being discharged from the combustion chamber of the fluidized bed heating boiler, the fluidizing medium used comprises a mixture of air and recirculating flue gases from the fluidized bed heating boiler, and the ratio of air and recirculating flue gases in the fluidizing medium is controlled such that the temperature of the flue gases above the fluidized bed is less than 890 ° C, preferably less than 850 ° C, more preferably less than 800 ° C, even more preferably less than 780 ° C and most preferably less than 750 ° C, and / or the flue gases are conducted to a first heat exchanger after being discharged from the fluidized bed heat boiler, the flue gases of the system being conducted to the surfaces of the heat exchanger located in the immediate vicinity of the flue gas inlet and / or to the surfaces of the heat exchanger located in the immediate vicinity of the flue gas inlet and perpendicular to the direction of flow of the flue gases so that the resulting temperature of the aforementioned flue gases is less than 830 ° C, preferably less than 780 ° C, more preferably less than 750 ° C, even more preferably less than 700 ° C, even more preferably less than 680 ° C, even more preferably less than 650 ° C and most preferably less than 620 ° C.

According to a particularly advantageous embodiment, the flue gases are led into a first heat exchanger after being discharged from the combustion chamber of the fluidized bed heating boiler, the secondary gas used exclusively comprises secondary air and / or a mixture of air and recirculated flue gases from the fluidized bed heating boiler, and in this case the supply of the aforementioned secondary air and / or the aforementioned mixture of air and recirculated flue gases from the fluidized bed heating boiler used as the secondary gas supplied to the fluidized bed heating boiler is controlled so that the temperature of the flue gases is downstream of the first and / or each possible subsequent secondary gas inlet is less than 980 ° C, preferably less than 950 ° C, more preferably less than 920 ° C, even more preferably less than 890 ° C, even more preferably less than 850 ° C, and most preferably less than 800 ° C, and / or top flue gases are conducted into the first heat exchanger after being discharged from the fluidized bed heat boiler, the amount of secondary air supplied to the combustion chamber of the fluidized bed heat boiler and / or the ratio of air and recirculating flue gases in the secondary gas supplied to the fluidized bed heat boiler layer is controlled in such a way that the temperature of the flue gases inside the first heat exchanger, in particular in the area where the flue gases are conducted to the surfaces of the heat exchanger located in the immediate vicinity of the flue gas inlet and / or to the surfaces of the heat exchanger located in the immediate vicinity of the inlet of flue gases and perpendicular to the direction of flow of flue gases is less than 850 ° C, preferably less than 830 ° C, more preferably less than 780 ° C, even more preferably less than 750 ° C, even more preferably less than 700 ° C, still more preferably less than 680 ° C, even more preferred its less than 650 ° C and most preferably less than 620 ° C.

It also turns out to be advantageous if the fluidizing medium used contains exclusively primary air or a mixture of air and recirculated flue gases from the thermal

- 7,038810 fluidized bed boiler, wherein the air contained in the above-mentioned mixture is preheated in a heat exchanger to preheat the air by means of flue gases discharged from the fluidized bed boiler before being introduced into the fluidized bed boiler and / or recirculation furnaces the gases contained in the aforementioned mixture are heated in a heat exchanger to heat the recirculated flue gases by means of flue gases discharged from the fluidized bed heat boiler before being introduced into the fluidized bed heat boiler.

In addition or as an alternative, the secondary gas used preferably contains exclusively secondary air or a mixture of air and / or recirculated flue gases from a fluidized bed heating boiler, wherein the air contained in the above mixture is preheated in a heat exchanger to preheat the air by means of combustion gases discharged from the fluidized bed heating boiler, before being introduced into the fluidized bed heating boiler, and / or the recirculating flue gases contained in the above mixture are heated in a heat exchanger to heat the recirculating flue gases by means of flue gases discharged from the fluidized bed heating boiler , before being introduced into a fluidized bed heating boiler.

In the case where steam is produced, it is advantageous if the flue gases discharged from the fluidized-bed heating boiler are conducted to a first heat exchanger, where the aforementioned flue gases flow over the surface of at least one superheater in the form of a heat exchanger for producing superheated steam, and then on the surface of at least one heater in the form of a heat exchanger for heating water and / or a mixture of steam and water supplied to the drum for supplying the superheater with steam, after which the flue gases are conducted into a second heat exchanger, where the aforementioned flue gases flow at least through one heat exchanger for heating the recirculated flue gases and through at least one heat exchanger for heating the air, after which the flue gases are passed through a filter, and then a correspondingly defined amount of flue gases are led into a pipeline for supplying a fluidizing medium to a thermal fluidized boiler bed and / or at least one heat exchanger for heating recirculating flue gases, from which the above-mentioned part of the flue gases is led into a pipeline for supplying a fluidizing medium to a fluidized-bed heat boiler, the said pipeline is provided with an inlet into which air is fed after passing through the aforementioned heat exchanger for heating the air.

In the case where a mixture of steam and water or hot water is obtained, it is advantageous if the flue gases discharged from the thermal fluidized bed boiler are conducted into a first heat exchanger, where the aforementioned flue gases flow over the surface of at least one heat exchanger to produce steam. , and then on the surface of at least one heater in the form of a heat exchanger for heating water and / or a mixture of steam and water supplied to the drum, after which the flue gases are conducted into a second heat exchange device, where the aforementioned flue gases flow through at least one heat exchanger for heating the recirculated flue gases and through at least one heat exchanger for heating the air, after which the flue gases are passed through a filter, and then a correspondingly defined amount of flue gases are led into a pipeline for supplying a fluidizing medium to a fluidized bed boiler and / or at least at least one a flat exchanger for heating recirculated flue gases, from which the aforementioned part of the flue gases is led into a pipeline for supplying a fluidizing medium to a fluidized bed heat boiler, the said pipeline being provided with an inlet into which air is fed after passing through the aforementioned heat exchanger for heating the air.

In the case where warm water is obtained, it is advantageous if the flue gases discharged from the thermal fluidized bed boiler are conducted into a first heat exchanger, where the above-mentioned flue gases flow over the surface of at least one heat exchanger for heating warm water, after which the flue gases the gases are led into a second heat exchanger, where the aforementioned flue gases flow through at least one heat exchanger for heating the recirculated flue gases and through at least one heat exchanger for heating the air, whereupon the flue gases are passed through a filter and then a suitably defined amount of flue gases is conducted into a pipeline for supplying a fluidizing medium to a thermal fluidized bed boiler and / or into at least one heat exchanger for heating recirculating flue gases, from which the aforementioned part of the flue gases are led into a pipeline for supplying a fluidizing medium to heat a howling fluidized bed boiler, the aforementioned conduit being provided with an inlet into which air is fed after passing through the aforementioned heat exchanger to heat the air.

Advantageously, secondary air is introduced into a line for supplying the combustion chamber with a secondary gas, the above-mentioned line is provided with an inlet into which the air is supplied after passing through the above-mentioned heat exchanger for heating the air, or into which the flue gases are supplied

- 8,038810 after passing through the aforementioned filter, wherein the aforementioned flue gases are passed to at least one heat exchanger for heating the recirculated flue gases.

Advantageously, flue gases are conducted over the surface of the heat exchanger to preheat water, which is then fed to the heater, before being fed to the heat exchanger for preheating the air by means of flue gases discharged from the fluidized bed heat boiler and / or to a heat exchanger for heating the recirculated flue gases by means of flue gases. gases discharged from a thermal fluidized bed boiler.

Advantageously, the temperature of the fluidizing medium blown into the fluidized bed heating boiler is less than 250 ° C, preferably less than 220 ° C, more preferably less than 200 ° C, even more preferably less than 180 ° C, even more preferably less than 160 ° C. even more preferably less than 140 ° C, even more preferably less than 120 ° C, and most preferably less than 100 ° C.

Advantageously, the temperature of the feed water supplied to the heat exchanger for preheating the water is at least 105 ° C, preferably at least 125 ° C, more preferably at least 145 ° C, even more preferably at least 180 ° C, even more preferably at least at least 195 ° C, even more preferably at least 210 ° C, and most preferably at least 230 ° C.

Thus, the claimed method of regulating the system of the boiler 1 with a fluidized bed prevents the useless increase in the temperature of the flue gases inside the combustion chamber above the absolutely necessary value and ensures the subsequent cooling of the flue gases at the maximum possible rate to ensure a sufficient decrease in the temperature of the flue gases upstream relative to the corresponding superheaters and heat exchangers. which are located in the transverse / perpendicular direction with respect to the direction of flow of the above-mentioned flue gases.

According to an advantageous embodiment, the superheaters are parallel-flow superheaters, which means that flue gases having the lowest possible temperature are passed through the parts of the superheaters having the highest temperature.

In a further advantageous embodiment, there is no lining in the system.

Due to the structural features and operation method of the above-mentioned fluidized bed heating boiler system according to the present invention, the temperatures of the superheaters can be increased above 420 ° C, preferably above 440 ° C, and more preferably above 460 ° C.

With regard to mitigating the effects of chloride-induced corrosion and deposits in the nozzles of the fluid grid, it is important to reduce the temperature of the fluidizing medium flowing through the nozzles of the aforementioned fluid grid. This objective is achieved by arranging heat exchangers for preheating air and flue gases together with a fan device, as mentioned in the description of the corresponding exemplary embodiment. This arrangement makes it possible to achieve optimum low temperature levels of the fluidizing medium so as to minimize the undesirable effects of corrosion and deposits.

The design and arrangement of heat exchange surfaces (in heat exchangers for heating air and recirculating flue gases) can also allow the temperature of the boiler feed water to rise without losing the ability to control chloride-induced fluidized bed boiler nozzle corrosion. In addition, as a result, the thermal efficiency of the steam cycle can be significantly increased.

The study of the phenomena described above continued for five years. For this purpose, a fluidized bed heat boiler was used, in which fuel containing up to 0.5% by weight of chlorine was fired. Chloride-induced corrosion of the superheater and unheated materials introduced into the environment containing flue gases from the combustion of the aforementioned fuel, namely, the region having a temperature below 700 ° C, did not occur during the prescribed temperature control procedures. In addition, crusts and deposits were not formed on the surfaces under consideration.

Brief description of the figures

FIG. 1 is a schematic diagram of a fluidized bed heating boiler system according to an exemplary embodiment of the present invention;

in fig. 2 is a photograph of a heat exchanger used with the fluidized bed heating boiler system of the present invention and showing no signs of deposits (chloride-induced corrosion);

in fig. 3A is a photograph of a heat exchanger showing signs of deposits;

in fig. 3B is a photograph of a heat exchanger where deposits have been removed and where exposed corroded surfaces are visible; and in FIG. 4 is a photograph of a plugged nozzle.

- 9 038810

Exemplary Embodiments of the Invention

According to the exemplary embodiment shown in the figures, the system comprises a fluidized bed heating boiler 1 having a combustion chamber into which fluidizing medium can be led from below through a series of fluidizing inlets 2.

Outlets of a pair of troughs 3, 4 open into the side wall of the heat boiler 1 with a fluidized bed. In plan view, the aforementioned outlets are spaced apart so that each outlet supplies an individual fuel or fuel mixture to a single region of the fluidized bed or to the space above the aforementioned bed. The upper parts of the troughs 3, 4 are provided with inlets 25, 26 for secondary air as well as for the carrier gas, the purpose of the latter being to increase the impulse of the fuel mixture supplied to the fluidized bed boiler 1. According to an advantageous embodiment, the troughs 3, 4 are tubular in shape. Secondary air inlets can also be introduced through the feed turnstiles 51, 52. In this case, the secondary air flow also contributes to the emptying of the feed turnstiles 51, 52.

In addition, the system comprises a pair of conveyors 5, 6. The first conveyor 5 opens into the first chute 3 and the second conveyor 6 opens into the second chute 4. In the present exemplary embodiment, the conveyors 5, 6 are worm conveyors. However, belt conveyors, scraper conveyors, vibratory conveyors, link conveyors or conveyors may be present in the simple form of a sufficiently large chute into which the fuel feeders 12, 13, 14, 15, 16, etc. open open.

In addition, the system contains fuel bins 7, 8, 9, 10, 11 and fuel feeders 12, 13, 14, 15, 16, and they are located as follows: the first fuel bunker 7 opens into the first fuel feeder 12, with two outlets of the last open into the first conveyor 5 and the second conveyor 6, respectively. Likewise, the second fuel hopper 8 opens into the second fuel feeder 13, with two outlets of the latter opening into the first conveyor 5 and the second conveyor 6, respectively. Likewise, the third fuel hopper 9, the third fuel feeder 14, the fourth fuel hopper 10, the fourth fuel feeder 15, the fifth fuel hopper 11, and the fifth fuel feeder 16 form respective pairs, which in turn are connected to the first and second conveyors 5, 6.

The thermal fluidized bed boiler system further comprises a storage tank 17 for CaCO ₃ , wherein one outlet of the aforementioned storage tank opens into a first conveyor 5, and its other outlet opens into a second conveyor 6, and a storage hopper 18 for inert material (i.e., non-combustible component of a fluidized bed such as sand), and wherein the aforementioned storage bin also has two outlets, the first outlet opening into the first conveyor 5 and the second outlet opening into the second conveyor 6. Alternatively, the outlets of the CaCO ₃ storage tank 17 and The storage hopper 18 for inert material can open directly into the combustion chamber of the thermal fluidized bed boiler 1.

At several points or at several levels, the secondary gas inlets 19 (the secondary gas may contain a mixture of secondary air and recirculated flue gases or clean secondary air) open into the fluidized bed boiler 1. According to the present exemplary embodiment, the upper section of the fluidized bed heating boiler 1 is further provided with an inlet 20 for additional combustion gas, in particular for natural gas, as well as an inlet 21 for a urea-based denitrification medium, the purpose of the aforementioned medium being to maintain a selective non-catalytic reduction process called DENOx.

The middle and lower sections of the fluidized-bed heating boiler 1 are provided with pilot burners 22. In addition, an adjustable ash removal device 23 is located in the lowermost section of the boiler, the outlet of the above-mentioned device opening into the ash conveyor 24.

The outlet of each conveyor 5, 6 is equipped with a rotary feeding device for fuel mixtures, such as a feeding device in the form of a feeding turnstile 51, 52, which separates the space of the combustion chamber from the fuel transport paths.

According to the present exemplary embodiment of the present invention, the flue gas outlet 29 of the system of the thermal fluidized bed boiler 1 is adjacent to a first heat exchanger 27 comprising a shell in which a plurality of heat exchangers are arranged stacked one on top of the other along the direction of the flue gas flow, namely a first superheater 28 , a second superheater 29 and a heater and / or evaporator 30. The arrangement of the aforementioned heat exchangers, which are connected to each other in the sequence described above, makes it possible to supply water from the source to the heat exchanger 33 for preheating the water (a so-called economizer, which is described in detail below) and further to the lower section of the drum 31, which is located (in the present configuration of the steam type) outside the first heat exchanger 27, from where the water is then passed through a conduit to the heater 30, and then (according to this embodiment, practically in the form of a mixture of steam and water) to the top the new section of the drum 31, then into the first superheater 28 and,

- 10 038810 finally to the second superheater 29, from where the superheated steam can be released for subsequent use.

The drum 31 is also provided with openings for connecting a heat exchanger outlet 48 forming at least part of the heat exchange surfaces (not illustrated) of the combustion chamber of the fluidized bed heat boiler 1, and a heat exchanger outlet 49 forming at least part of the shell / heat exchange surfaces (also not illustrated) the first heat exchanger 27. The aforementioned heat exchangers, which are not illustrated in the figure, may be heat exchangers for steam, hot water or warm water, preferably consisting of diaphragm / tubular walls.

Advantageously, the superheaters 28, 29 can be designed as vertical tube bundle heat exchangers with longitudinal flow direction, preferably parallel flow heat exchangers. In this configuration, no transverse tube bundles are installed underneath the heat exchangers, where the blown off adhesive might otherwise form deposits. According to the present exemplary embodiment, the superheaters 28, 29 are tube bundle heat exchangers that are disposed in the lateral direction, i. E. perpendicular to the direction of the flue gas flow.

The combustion process and subsequent exhaust of flue gases can be advantageously controlled so as to maintain a temperature in the combustion chamber that does not exceed 950 ° C, preferably 930 ° C, more preferably 900 ° C, more preferably 870 ° C, more preferably 850 ° C, even more preferably 800 ° C and most preferably 770 ° C; and at the same time that the temperature of the flue gases supplied to the superheaters does not exceed 850 ° C, preferably 800 ° C, more preferably 780 ° C, more preferably 750 ° C, more preferably 720 ° C, more preferably 700 ° C, more preferably 680 ° C, more preferably 650 ° C and most preferably 620 ° C.

In the case where specific waste is incinerated, such as segregated municipal waste or sludge from a waste water treatment plant, it is necessary to maintain the temperature in the combustion chamber above 850 ° C, with a delay in flue gas removal of two seconds. Hereinafter, a system will be described for maintaining the aforementioned temperature or other temperatures.

With regard to possible temperature fluctuations inside the combustion chamber and thus to temperature fluctuations of the flue gases supplied to the superheaters 28, 29, it is advantageous if suitable steam nozzles (not illustrated) are opened into the first heat exchanger 27, the aforementioned nozzles sometimes being suitable for cleaning the heat exchange surfaces of heat exchangers, in particular for removing ash and adhesive from the heat exchange surfaces of superheaters 28, 29.

According to further embodiments, which are not shown in the figures, some parts of the first device 27 may or may not be different (in particular with respect to the final water / steam temperature requirements); for example, drum 31, first and / or second superheaters 28, 29, etc. may be missing.

The flue gas outlet of the first heat exchanger 27 opens into a second heat exchanger 32, including a shell, in which there is a heat exchanger 33 for preheating the water supplied to the drum 31, a heat exchanger 34 for heating the recirculated flue gases introduced into the secondary air for the purpose of producing secondary gas, a heat exchanger 35 for preheating the recirculated flue gases introduced into the primary air for the formation of a fluidizing medium, a heat exchanger 36 for heating the secondary air before it is introduced into a fluidized bed heat boiler and a heat exchanger 37 for preheating the primary air, the aforementioned heat exchangers located in the flow of the furnace gases (most preferably in the sequence described above along the direction of flow of the flue gases). The second heat exchanger 32 also does not need to contain all of the components shown. This means, for example, that there may be no heat exchanger 33 for preheating water and / or a heat exchanger 34 for heating recirculated flue gases introduced into the secondary air for the purpose of producing secondary gas, etc. Other sequences of heat exchangers 34 to 37 are also possible, but the configuration described above is considered to be the most advantageous.

The flue gas outlet from the second heat exchanger 32 is connected to the chimney 42 through a filter 40 and a flue gas exhaust fan 41.

The air supply to the heat exchanger 37 for preheating the primary air is provided by the primary fan 43. The air supply to the heat exchanger 36 for the preheating of the secondary air is provided by the secondary fan 44. The supply of recirculated flue gases to the heat exchanger 35 for preheating the recirculated flue gases that are added to the primary air as a component of the fluidizing medium introduced into the fluidized-bed heating boiler 1 is provided by means of a first recirculation fan 45, which is connected to the filter outlet line 40 and / or to the outlet

- 11 038810 by means of a flue gas venting fan 41. The supply of recirculated flue gases to the heat exchanger 34 for heating the recirculated flue gases, which are added to the secondary gas before it is introduced into the fluidized bed boiler 1, is provided by means of a second recirculation fan 46, which is also connected to a filter outlet line 40 and / or with a flue gas outlet fan 41 outlet line.

Obviously, it will not become necessary to use all of the aforementioned heat exchangers, which means that one of the flue gas heat exchangers with air or flue gas heat exchangers with gas, i.e. heat exchangers that heat / preheat air or recirculated flue gases may not be available, or alternatively it may be designed differently than a heat exchanger that uses air or recirculated flue gases. For example, additional air streams can be heated to preheat the ambient air. Another alternative is the use of a heat exchanger for heating water by means of flue gases, where warm or hot water is used to apply the recirculated heat in a different way than described above. However, the proposed system is considered to be the most advantageous.

The device shown in FIG. 1, additionally contains temperature sensors T, pressure gauges P and flow meters Q.

The system additionally contains a control unit (not illustrated), which is connected to the conveyors 5, 6 to regulate their speeds, to the fuel feeders 12-16 to regulate the corresponding fuel supply processes, to the storage tank 17 for CaCO ₃ , to the storage hopper 18 for inert material , as well as at least some of the temperature sensors T, pressure gauges P and flow meters Q. In addition, the specified control unit can be connected to the supply turnstiles 51, 52, as well as valves and / or fans for regulating the supply of fluidizing medium to fluidizing inlets 2 or to regulate the supply of primary air and recirculated flue gases to a common pipeline for supplying a fluidizing medium to a fluidized bed boiler 1, to regulate the operation of secondary gas inlets 19 (and, as the case may be, to regulate the amount of recirculated flue gases added to the secondary air), for regulating the operation of the inlet 20 for supplying additional combustible gas; and for regulating the operation of the inlet 21 for supplying the denitrification medium to the fluidized-bed heating boiler 1.

During the operation of the system shown in the figure, CaCO ₃ , fuel and inert material are continuously fed to conveyors 5, 6. (Alternatively, CaCO ₃ and inert material can be fed directly into the combustion chamber of a thermal fluidized bed boiler.) Fuel mixture composition are controlled in such a way that different types of fuel are dosed and then supplied at a certain rate, the above-mentioned rate corresponding to a certain mass or volume per unit of time. This is carried out by means of feeders 12, 13, 14, 15, 16, and the installation of the latter determines the mutual ratios of the content of various types of fuel in the final fuel mixture supplied to the heat boiler 1 with a fluidized bed. Thus, in the fluidized bed heating boiler 1 according to the present exemplary embodiment, a continuous stream is fed through the troughs 3, 4 containing layers of CaCO ₃ , inert materials and fuel of several types at a constant ratio. For this reason, no fluidized bed regions are formed that have significantly different compositions, and no processing problems arise that would be caused by non-uniformity of the fuel in the fluidized bed.

The amounts of various types of fuel and / or additives, as well as the arrangement of the respective layers, can also be adjusted by means of the feeders 12, 13, 14, 15, 16, which are installed on the conveyors 5, 6, in particular, taking into account the mode in which the carrier gas is supplied to the corresponding chute 3, 4, as well as taking into account the different volumetric densities of the fuel. The purpose of the above regulation is to prevent the carrier gas from separating the individual components by blowing layers having lower densities into different regions, and to prevent components having lower densities from being forced out into the upper sections of the combustion chamber of the fluidized bed heat boiler 1, i.e. .e. into the section above the fluidized bed.

When the conveyors 5, 6 used are worm-type conveyors, as is the case according to the present exemplary embodiment, the supplied fuel and additives are advantageously mixed with each other. Such a worm conveyor can be positioned to allow the individual fuel feeders 12-16 and the individual additive lines to open into respective individual or common worm conveyor inlets, or open onto a conveyor belt leading to the worm conveyor inlet, and as a result all components can be mixed on the final path leading to the combustion chamber of the fluidized bed heating boiler and fed into the corresponding chute 3, 4.

If, for example, the conveyor 5, 6 is a worm-type conveyor, the different types of fuel are always placed on such a conveyor 5, 6 in the form of continuous layers having precisely metered volumes (or weights or ratios). This means that, although the constituents of the fuel mixture,

- 12 038810 supplied to the combustion chamber do not mix with each other, the composition of the mixture is constant at any moment (or in any short period of time), and these ratios between different types of fuel and / or additives remain unchanged.

The fuel that can be fed to the individual storage bins contains RDF (fuel derived from segregated municipal waste), lignite, coal, wood chips, wood-based pellets, pellets (or briquettes) of agricultural biomass, fuels derived from sludge water treatment plants, fuels obtained from the processing of food and biomass (such as lignin, bran, straw), etc.

The fuel supplied to the combustion chamber can advantageously be metered, for example, as follows:

0 to 90%, preferably 0 to 40% RDF (Separated Municipal Waste Fuel), 0 to 90%, preferably 0 to 40% brown coal, 0 to 90%, preferably 0 to 40% coal, 0 to 90%, preferably 0 to 40% wood chips, 0 to 90%, preferably 0 to 40% agricultural biomass pellets, 0 to 90%, preferably 0 to 40% wood pellets.

The following illustrative examples relate to fuel mixtures that can be combusted in a fluidized bed thermal boiler system according to the present invention or according to a method according to the present invention.

Mix 1.

RDF 30% (where RDF stands for fuel derived from segregated municipal waste), lignite 20%, bituminous coal 25%, wood chips 20%, Ekover pellets 5% (i.e. pellets derived from plant materials such as fragments seeds, surface layers of seeds, non-standard seeds, straw chaff, flower scales, awn, fragments of other parts of plants, seeds of weeds and uncultivated plants, crumbs of biological materials, etc.).

Mix 2.

RDF - 50%, brown coal - 10%, wood chips - 20%, agricultural biomass pellets - 20%.

Mix 3.

RDF - 70%, brown coal - 5%, wood chips - 25%, agricultural biomass pellets - 0%.

Mix 4.

RDF - 10%, brown coal - 10%, hard coal - 5%, wood shavings - 50%, agricultural biomass pellets - 25%.

Mix 5.

RDF - 35%, coal - 5%, wood shavings - 50%, wood pellets - 10%.

According to the exemplary embodiment shown, two conveyors 5, 6 are used. Of course, it is possible to use only one conveyor 5, or alternatively three or more conveyors depending on the horizontal projection area of the combustion chamber or fluidized bed in the fluidized bed heat boiler 1.

As a rule, it turns out to be advantageous if the system is equipped with at least one inlet for supplying the fuel mixture to the combustion chamber of the thermal fluidized bed boiler 1, and / or at least one conveyor 5, 6, and / or at least one chute 3, 4 based on a plan area of 20 m ² , preferably 18 m ² , more preferably 16 m ² , even more preferably 12 m ² , even more preferably 10 m ² , even more preferably 8 m ² and most preferably 6 m ² . It also turns out to be advantageous if the system is provided with no more than one inlet for supplying fuel to the combustion chamber, or no more than one conveyor 5, and / or no more than one chute 3, based on a plan area of 3 m ² .

- 13 038810

In the present embodiment, five fuel bins 7-11 and five corresponding fuel feeders 12-16 are used. Of course, the system can be equipped with a different number of storage bins 7-11 and fuel feeders 12-16. According to a further embodiment, one storage hopper 7 can serve to fill two or more fuel feeders 12-16, and it is especially advantageous if the fuel feeders 12-16 have a sufficiently large inlet space to allow one of the aforementioned storage hopper 7 to alternately supply / replenish fuel for example, for at least two of the fuel feeders 12-16.

In the embodiment shown, each of the fuel feeders 12-16 is provided with two outlets, one outlet serving for loading onto the first conveyor 5 and the other outlet serving for loading onto the second conveyor 6. In another embodiment, each storage hopper 7 can be connected to one a pair of feeders, each of the aforementioned feeders belonging to one conveyor 5, 6. Alternatively, a corresponding number of fuel bins and fuel feeders can be provided for each conveyor 5, 6, and the outlets of such bins and feeders open exclusively to this conveyor 5, 6.

Secondary air and carrier gas inlets 25, 26, respectively, the purpose of the latter gas being to increase the momentum of the fuel mixture supplied to the fluidized bed boiler 1, are connected to a secondary fan 44 for cold or unheated secondary air into the combustion chamber. Due to the aforementioned arrangement, the temperature at the fuel supply inlet to the combustion chamber of the fluidized bed heat boiler 1 can be controlled by adjusting the amount of secondary air (preferably cold air) through the fuel and heated secondary air supply inlets, and also by adjusting the temperature inside the combustion chamber, wherein the latter regulation is carried out by means of a secondary gas supplied through inlets 19. According to another advantageous embodiment, recirculated flue gases can be introduced into inlets 25 or 26 to reduce the oxygen content in the fuel supply regions, and / or warm or cold recirculated flue gases can be introduced through the inlet 19 to control the temperature of the flue gases in the combustion chamber of the fluidized bed heat boiler 1.

Secondary air inlets 25, 36 may be missing in accordance with the type of fluidized bed boiler 1 and / or the types of fuel used and / or the type of chute 3, 4. Alternatively, only one of the above inlets may be missing, or on the contrary, the number of the aforementioned inlets can be increased.

Likewise, inlets 19 for supplying secondary air or recirculating flue gases may be omitted according to the type of fluidized bed boiler 1 and / or the types of fuels used. Alternatively, only one of the aforementioned inlets may be missing, or, on the contrary, the number of the aforementioned inlets can be increased.

During the combustion process according to the present invention, the temperature of the fluidized bed can be controlled by adjusting the ratio of the amount of air and the amount of recirculated flue gases in the fluidizing medium, i.e. by regulating the amount of oxygen supplied to the combustion chamber. Simultaneously, the temperature of the fluidized bed is influenced by the amount of heat released through the heat exchange surfaces.

The temperature in the space of the combustion chamber above the fluidized bed can be controlled by adjusting the amount of secondary air supplied to the above-mentioned space at different levels, i.e. through individual inlets. During the combustion process, combustible gas, in particular CO, or a mixture of combustible gases such as CO, H ₂ , methane and higher hydrocarbons, will exit the fluidized bed. Thereafter, such combustible gases will burn or will burn, depending on the amount of oxygen present / supplied. Combustion of the aforementioned combustible gases of gas mixtures over the fluidized bed will affect the temperature in this area. This means that the desired temperature for a certain level of the combustion chamber can be achieved by adjusting the amount of oxygen, i. E. secondary air supplied at this level. The use of certain fuel mixtures can cause some of the fuel to randomly fly out and then burn over the fluidized bed instead of burning inside the bed. In this case, oxygen must be supplied through the secondary air inlets. However, this combustion method undesirably increases the temperature above the fluidized bed. Consequently, the temperature must be reduced by adding recirculated flue gases to the secondary gas. The secondary gas can be supplied at individual levels of the combustion chamber above the fluidized bed (or at least at one level), the said secondary gas being present in the form of a mixture of secondary air and recirculated flue gases. Alternatively, secondary air and recirculated flue gases can be fed separately into the space above the fluidized bed. In both cases, the amount supplied can be adjusted depending on the required temperatures and the expected oxygen consumption in the space above the fluidized bed.

- 14 038810

The above-described method for controlling the temperature at different levels of the combustion chamber is particularly advantageous because it allows different fuel mixtures to be burned in a fluidized bed thermal boiler 1 and to continuously change from one type of mixture to another without the need to take the boiler out of operation. In addition, the temperatures in the combustion chamber and along the downstream flue gas flow path must be controlled in such a way as to eliminate or at least substantially inhibit chlorine and chloride-induced corrosion. This turns out to be especially important in the case where fuel is burned with a significant chlorine content, such as fuel derived from segregated municipal waste and from agricultural biomass. When specific waste is incinerated, such as segregated municipal waste or sludge from a waste water treatment plant, the temperature in the combustion chamber must be maintained, in addition to the above requirements, above 850 ° C, with a delay in flue gas removal of at least two seconds.

For the purpose of the aforementioned temperature control, a control unit can advantageously be used, the aforementioned control unit must be configured to receive temperature data from various sensors and to control valves and / or fans 43, 44, 45, 46 used for supplying air and recirculating flue gases to the inlets for supplying fluidizing medium and / or to inlets for supplying secondary gas / air, and / or to the troughs 3, 4, or to ensure the corresponding regulation of the above-mentioned valves and / or fans, and the above-mentioned regulation should be based on the data obtained from the aforementioned sensors, and as the case may be, from the incoming data on the currently supplied fuel mixture (the latest data includes, for example, the estimated chlorine content).

With regard to the variability of the fuel composition, it will be beneficial to select appropriately enlarged inlet sizes for the fluidizing medium and for the secondary gas. The same condition applies to the respective fans 43, 44, 45, 46 used to adapt the atmosphere inside the combustion chamber of the fluidized bed heating boiler 1 to the fuel mixture currently supplied.

Thus, with regard to the variability of the fuel composition, it will also be beneficial to select appropriately increased temperature values of the heat exchangers 35, 37 in order to eliminate the effects of chlorine and chloride-induced corrosion on the nozzles of the fluid grid, which is especially important when using fuels containing organic or inorganic chlorine compounds. In this regard, the requirements for increasing the thermal efficiency of the steam cycle and the corresponding requirements for increasing the temperature of the feed water used for fluidized bed heating boilers are of particular importance, with the usual temperature of the above-mentioned feed water being 105 ° C, and / or the temperature of the above-mentioned feed water is preferably more than more than 125 ° C and / or more than 145 ° C and / or more than 180 ° C and / or more than 195 ° C and / or more than 210 ° C and / or more than 230 ° C.

It also turns out to be advantageous if the heat exchangers 34, 35, 36, 37 are equipped with suitably enlarged fans, which take part in the regulation of the temperature of the fluidizing medium and in the adaptation of the atmosphere in the combustion chamber of the thermal fluidized bed boiler 1 to the composition of the fuel mixture supplied to the this moment.

The temperature of the fluidizing medium significantly affects the degree of corrosion to the nozzles of the fluidizing grid. As a result of this corrosion, sticky spots and deposits of various salts, in particular K, Na and Ca compounds with chlorine, are formed, and the above-mentioned deposits show a significant tendency to spread. These sticky spots gradually build up, and as a result, the nozzles are completely clogged. During the above process, the adhesive spots spread (grow) and gradually clog the nozzle openings, making them unusable. Failure of the nozzles (inlets 2) leads to the subsequent failure of the boiler grate and, in turn, of the thermal fluidized bed boiler 1 itself.

During operation studies carried out by the applicants, it was found that the temperature of the fluidizing medium has the most significant effect on the formation and development of sticky spots on the nozzles of the fluidized bed boiler 1, and the decrease in temperature leads to a decrease in the formation of sticky spots, which allows to increase the intervals between the corresponding operations. for cleaning.

Thus, it is desirable to keep the temperature of the fluidizing medium at the lowest possible level of less than 250 ° C, preferably less than 220 ° C, more preferably less than 200 ° C, even more preferably less than 180 ° C, even more preferably less than 160 ° C. , even more preferably less than 140 ° C, even more preferably less than 120 ° C, and most preferably less than 100 ° C. Advantageously acceptable temperatures of the fluidizing medium can be achieved with a plurality of heat exchangers 34, 35, 36, 37, as described above. In this regard, it turns out to be advantageous to manufacture the heat exchanger 36 for heating the secondary air, the maximum possible dimensions (namely, the dimensions of the heat exchange

- 15,038810 surfaces and corresponding outputs), in particular to the extent that allows the heat exchanger to remove more heat from the flue gases in comparison with the heat exchanger 37 for heating the primary air (added to the fluidizing medium) and with the heat exchanger 35 for heating the primary recirculation furnaces. gases (added to the fluidizing medium).

The effects of high temperature and low temperature corrosion caused by chlorine can be largely mitigated (eliminated) by adding limestone to the fuel, which addition causes the chlorine to react with the limestone in the fluidized bed and form CaCl2. Chlorine-induced corrosion can be converted to chloride-induced corrosion, which can be successfully inhibited by providing specified temperatures and procedures as mentioned above.

In the photograph of FIG. 2 shows an example of a heat exchanger without sticky spots, i.e. free of chloride-induced corrosion, which has been subjected to a temperature controlled operation test in accordance with the present invention. FIG. 3A shows a similar heat exchanger which lacks control of the flue gas feed temperature and the temperature of the flue gases discharged from the combustion chamber, and therefore suffers from unwanted sticky spots / chloride-induced corrosion. The formation of sticky spots leads to a simultaneous significant decrease in heat transfer efficiency and destruction of the pipe material of the respective heat exchanger. This means that corrosion occurs underneath the sticky spots, which are clearly visible in FIG. 3B which shows the heat exchanger where the adhesive spots have been removed. Finally, in the photograph of FIG. 4 shows the nozzles / inlets 2, which have received a fluidizing medium having a temperature exceeding 250 ° C, or an uncontrolled temperature. Consequently, the nozzles were gradually clogged with adhesive.

When fuels containing organic or inorganic chlorine compounds are used, the combustion process and subsequent exhaust of flue gases can be advantageously controlled in a manner such that the temperature in the combustion chamber does not exceed 950 ° C, preferably 930 ° C, more preferably 900 ° C, more preferably 870 ° C more preferably 850 ° C, even more preferably 800 ° C, and most preferably 770 ° C; and at the same time that the temperature of the flue gases supplied to the superheaters or to the first heat exchangers, which are affected by the respective flue gas streams, does not exceed 850 ° C, preferably 800 ° C, more preferably 780 ° C, more preferably 750 ° C, more preferably 720 ° C, more preferably 700 ° C, more preferably 680 ° C, even more preferably 650 ° C, and most preferably 620 ° C.

Heat exchangers, in particular tubular cross-flow heat exchangers, do not suffer from the formation of sticky spots or can be easily cleaned of such sticky spots by means of nozzles, provided that the temperature of the flue gases supplied to the heat exchanger is preferably less than 800 ° C, preferably less than 720 ° C and most preferably less than 620 ° C.

The present invention proves to be advantageously applicable especially in thermal fluidized-bed boilers, where the fixed fluidized bed has a plan area of more than 5 m ² , preferably more than 10 m ² , preferably more than 15 m ² , preferably more than 20 m ^2. , preferably more than 30 m ² , and in thermal fluidized-bed boilers, where the fixed fluidized bed has a horizontal area of more than 10 m ² , preferably more than 15 m ² , preferably more than 20 m ² , preferably more than 30 m ² , preferably more than 40 m ² .

Consider a schematic diagram showing a fluidized bed heat boiler 1 system where the exhaust medium is steam discharged from a second superheater 29. In an embodiment that is not illustrated, one of the superheaters 28, 29 may be missing. According to another embodiment, which is also not illustrated and in which hot water is required at the outlet, both superheaters 28, 29 can be omitted and water can be led from heater 30 to drum 31, then to a heat exchanger consisting of heat exchange walls inside the combustion chamber. and finally back to the drum 31, whereby hot water can be discharged from the drum 31. According to a further embodiment, which is also not illustrated, and in which the presence of hot water is required at the outlet, the superheaters 28, 29 together with the drum 31 may be absent, and water can be discharged from the heater 30 into a heat exchanger consisting of heat exchange walls inside the combustion chamber, and then into the outlet of the system of the thermal fluidized bed boiler 1.

Thanks to the claimed design, which is described above, it is possible to simultaneously feed the heating boiler 1 with a fluidized bed with fuel of several types with different combustion characteristics or different chemical compositions of the fuel itself or the corresponding ash, and the proportional content of individual fuel in the total amount of fuel can continuously change together with technological characteristics, where the aforementioned characteristics include, in particular, the temperature and the amount of fluidizing medium and, as the case may be, can be the characteristics of the secondary gas or secondary air.

Claims (18)

CLAIM 1. A fluidized bed boiler system, comprising a fluidized bed heat boiler (1), comprising a combustion chamber; a first conveyor (5) for supplying the first fuel mixture to the fluidized bed heat boiler (1) and / or for loading the fuel mixture into the combustion chamber; a first fuel feeder (12) for supplying a first fuel and a second fuel feeder (13) for supplying a second fuel that differs from the first fuel in combustion characteristics or chemical composition, wherein the first outlet of the first feeder (12) and the first outlet of the second feeder (13) open on the surface or inside the first conveyor (5) in close proximity or at a distance from each other, characterized in that at least one of the fuels is selected from the group consisting of fuels obtained from separated municipal waste, wood chips, wood-based pellets, coconut shells, pellets or briquettes of agricultural biomass, fuels obtained from the sludge of wastewater treatment plants, fuels obtained from the processing of food products, forage plants and biomass, fuels obtained from agricultural waste, fuels obtained from waste oils or grain alcohols, in particular, from distillation residues, or fuel, we obtain th of lignin, bran, straw or agricultural manure, and the system further comprises a feed channel for a fluidizing medium, and the aforementioned feed channel opens into the fluidizing inlets (2) of the combustion chamber of the thermal boiler (1) with a fluidized bed, and at least one feed channel (19) for secondary air or for secondary gas; and a control unit configured to regulate the supply of secondary gas that enters the fluidized bed boiler (1) and contains secondary air or a mixture of air and recirculated flue gases discharged from the fluidized bed boiler (1), so that the temperature of the flue gases downstream of the first and / or each possible subsequent secondary gas inlet is less than 980 ° C. 2. A fluidized bed boiler system according to claim 1, characterized in that the first outlet of the first feeder (12) and the first outlet of the second feeder (13) open to the surface or into the first conveyor (5) in the immediate vicinity or at a distance from each other to allow the fuel supplied by the second feeder (13) to be stacked on the fuel supplied by the first feeder (12), and / or the system further comprises a first fuel hopper (7), the outlet of which is connected to the inlet of the first fuel feeder (12), and the second fuel hopper (8), the outlet of which is connected to the inlet of the second fuel feeder (13). 3. A fluidized bed boiler system according to claim 1, characterized in that the system further comprises a storage tank (17) for CaCO ₃ and / or a storage tank (18) for inert fluidized bed material, and the outlets of the above storage tanks (17, 18 ) open to the surface or to the inside of the first conveyor located at a distance from the outlets of the first and / or second feeders (12, 13). 4. A fluidized bed boiler system according to claim 1, characterized in that the system further comprises a second conveyor (6) for loading the fuel mixture into the combustion chamber in an area located at a certain distance from the area where the mixture supplied by the first conveyor (5 ), wherein the second outlet of the first feeder (12) and the second outlet of the second feeder (13) open to the surface or inward of the aforementioned second conveyor (6), and the aforementioned outlets are located in close proximity or at a distance from each other. 5. A fluidized bed boiler system according to claim 1, characterized in that the system further comprises a first chute (3) opening into the combustion chamber of the fluidized bed boiler, wherein the inlet of said first chute (3) is connected to the outlet of the first conveyor (5 ). 6. A fluidized bed boiler system according to claim 5, characterized in that the system further comprises a second chute (4) opening into the combustion chamber of the fluidized bed heat boiler (1), the inlet of said second chute (4) being connected to the outlet of the second conveyor (6), and the outlets of the first and second chutes (3, 4) are located at a distance from each other when viewed in horizontal projection. 7. A fluidized bed boiler system according to claim 6, characterized in that the system further comprises a first feed turnstile (51) for loading the fuel mixture supplied by the first conveyor (5) into the first chute (3) and the second feed turnstile (41) for loading the fuel mixture supplied by the second conveyor (6) into the second chute (4). 8. A fluidized bed boiler system according to claim 1, characterized in that the system further comprises a first heat exchange device (27) having a flue gas inlet connected to a flue gas outlet of a fluidized bed heat boiler (1) and comprising at least one heat exchanger for heating water and / or for heating a mixture of steam and water and / or for heating - 17,038810 steam by means of flue gases discharged from the thermal fluidized bed boiler (1) and conducted over the surface of at least one heat exchanger mentioned above. 9. A fluidized bed boiler system according to claims 7 and 8, characterized in that the system further comprises a second heat exchanger (32) having a flue gas inlet connected to the flue gas outlet of the first heat exchanger (27), wherein said second heat exchanger (32) comprises a heat exchanger (36) for heating the secondary air, and the outlet of the aforementioned heat exchanger (36) can be connected to at least one channel (19) for supplying the thermal fluidized bed boiler (1) with secondary air; and / or a heat exchanger (37) for heating the primary air, wherein the outlet of the aforementioned heat exchanger (37) can be connected to the fluidizing inlets (2), and wherein the heat exchanger (36) for heating the secondary air is located with respect to the direction of flow of the flue gases through a second heat exchanger (32), upstream of the heat exchanger (37), for heating the primary air. 10. A fluidized bed boiler system according to claim 9, characterized in that the system further comprises a control unit adapted, based on the ratio of the output powers of the heat exchangers (36, 37) contained in the second heat exchanger (32), to regulate the air ratio and recirculating flue gases in a fluidizing medium supplied to the fluidizing inlets (2) such that the temperature of the fluidizing medium passed through the fluidizing inlets (2) is less than 250 ° C, preferably less than 220 ° C, more preferably less than 200 ° C, even more preferably less than 180 ° C, even more preferably less than 160 ° C, even more preferably less than 140 ° C, even more preferably less than 120 ° C and most preferably less than 100 ° C, and / or such that the temperature flue gas above the fluidized bed is less than 890 ° C, preferably less than 850 ° C, more preferably less than 800 ° C, even more preferably less than 780 ° C and most preferably less than 750 ° C, and / or the control unit is configured to regulate the supply of secondary gas that enters the fluidized bed boiler (1) and contains secondary air or a mixture of air and recirculated flue gases discharged from heat boiler (1) with a fluidized bed, such that the temperature of the flue gases downstream of the first and / or each possible subsequent inlet of secondary gas is less than 950 ° C, preferably less than 920 ° C, even more preferably less than 890 ° C, even more preferably less than 860 ° C and most preferably less than 800 ° C, and / or such that the temperature of the flue gases inside the first heat exchanger (27) in the region where the flue gases are conducted to the surfaces of the heat exchanger located in the immediate vicinity to the flue gas inlet and / or to the surfaces of the heat exchanger located in the immediate vicinity of the flue gas inlet ov, and perpendicular to the direction of flow of flue gases is less than 850 ° C, preferably less than 830 ° C, more preferably less than 780 ° C, even more preferably less than 750 ° C, even more preferably less than 700 ° C, still more preferably less than 680 ° C, even more preferably less than 650 ° C, and most preferably less than 620 ° C. 11. A method for the simultaneous combustion of at least two types of fuel in a fluidized bed heating boiler (1) by means of a fluidized bed boiler system according to claim 1, wherein the fluidizing medium is blown from below into the fluidized bed heating boiler (1), the first fuel is fed by the first feeder (12) to the surface or inside the first conveyor (5) and transported by the first conveyor (5) into the fluidized bed heat boiler (1), and then loaded into the combustion chamber of the fluidized bed heat boiler (1), the second fuel is supplied the second feeder to the surface or inside the first conveyor (5), and the area for supplying the first fuel is located next to the area for supplying the second fuel or at a distance from it, and the second fuel and the first fuel are transported by the first conveyor (5) to the heat boiler ( 1) with a fluidized bed, and then loaded together into the combustion chamber of a thermal boiler (1) with a fluidized bed, characterized in that at least one of fuels selected from the group consisting of fuels derived from segregated municipal waste, wood chips, wood-based pellets, coconut shells, agricultural biomass pellets or briquettes, fuels derived from sludge from wastewater treatment plants, fuels derived from food processing, fodder plants and biomass, fuels obtained from agricultural waste, fuels obtained from waste oils or grain alcohols, in particular from bottoms, or fuels obtained from lignin, bran, straw or agricultural manure, and the regulating unit regulates the supply of secondary gas that enters the fluidized bed heat boiler (1) and contains secondary air or a mixture of air and recirculated flue gases discharged from the fluidized bed heat boiler (1), such that the temperature of the flue gases is downstream of the first and / or every possible pos the next inlet of the second - 18,038810 ric gas is less than 980 ° C. 12. The method according to claim 11, characterized in that the other fuel is selected from the group consisting of fuel obtained from separated municipal waste, preferably fuel in granular form, brown coal, coal, petroleum coke, wood chips, wood pellets base, coconut shells, pellets or briquettes of agricultural biomass, fuels derived from sludge from wastewater treatment plants, fuels derived from the processing of food, forage plants and biomass, fuels derived from agricultural waste, fuels derived from oil or grain production waste alcohols, in particular from bottoms, or fuels obtained from lignin, bran, straw or agricultural manure. 13. A method according to claim 11, characterized in that the fluidizing medium is blown into the fluidized bed heating boiler (1) through corresponding inlets (2) and the secondary gas is blown into the fluidized bed heating boiler (1) at at least one height level above the level of the fluidizing medium inlets (2), preferably at at least two different heights, more preferably at least two different heights. 14. The method according to claim 11, characterized in that the flue gases discharged from the thermal fluidized bed boiler (1) are conducted into a first heat exchanger (27) containing at least one heat exchanger for heating water and / or for heating the mixture steam and water and / or for heating the steam by means of flue gases discharged from a thermal fluidized bed boiler (1), after which the aforementioned flue gases are conducted into a second heat exchanger (32), in which flue gases flow over the surface of at least one heat exchanger (36) for heating the secondary air, and then on the surface of at least one heat exchanger (37) for heating the primary air, and the air heated in the heat exchanger (37) for heating the primary air is supplied to the fluidizing inlets (2) of the heat boiler (1 ) with a fluidized bed, and the air heated in the heat exchanger (36) for heating the secondary air is fed to the heat boiler (1) with a fluidized bed at least at least on the same level for supplying the secondary gas to the fluidized bed boiler (1). 15. A method according to claim 14, characterized in that the temperature of the fluidizing medium supplied through the fluidizing inlets (2) is controlled so that it is less than 250 ° C, preferably less than 220 ° C, more preferably less than 200 ° C , even more preferably less than 180 ° C, even more preferably less than 160 ° C, even more preferably less than 140 ° C, even more preferably less than 120 ° C and most preferably less than 100 ° C, and / or in that the temperature of the flue gases above the fluidized bed is less than 890 ° C, preferably less than 850 ° C, more preferably less than 800 ° C, even more preferably less than 780 ° C and most preferably less than 750 ° C, and / or a secondary gas feed that enters the fluidized bed heat boiler (1) and contains secondary air or a mixture of air and recirculated flue gases discharged from the fluidized bed heat boiler (1), is controlled so that the flue gas temperature is downstream of with respect to the first and / or each possible subsequent secondary gas inlet is less than 950 ° C, more preferably less than 920 ° C, even more preferably less than 890 ° C, even more preferably less than 860 ° C, and most preferably less than 800 ° C, and / or the secondary gas supply is controlled such that the temperature of the flue gases inside the first heat exchanger (27) in the area where the flue gases are conducted to the surfaces of the heat exchanger located in the immediate vicinity of the flue gas inlet and / or to the surfaces of the heat exchanger located in the immediate vicinity to the flue gas inlet and perpendicular to the flue gas flow direction is less than 850 ° C, preferably less than 830 ° C, more preferably less than 780 ° C, even more preferably less than 750 ° C, even more preferably less than 700 ° C , even more preferably less than 680 ° C, even more preferably less than 650 ° C, and most preferably less than 620 ° C. 16. A method according to claim 11, characterized in that the fluidizing medium comprises primary air or a mixture of air and recirculated flue gases from a thermal fluidized bed boiler (1), wherein the air contained in said mixture is preheated in a heat exchanger (37) for preheating the air by means of flue gases discharged from the fluidized bed heating boiler (1), before being introduced into the fluidized bed heating boiler (1), and / or the recirculating flue gases contained in the above mixture are heated in a heat exchanger to heat the recirculating flue gases by means of flue gases discharged from the fluidized bed heating boiler (1), before being introduced into the fluidized bed heating boiler and / or the secondary gas contains secondary air or a mixture of air and recirculating flue gases from the fluidized bed heating boiler (1), the air being contained in the above mixture, preheated in those flat exchanger (36) for preheating the air by means of flue gases discharged from the thermal fluidized bed boiler (1), before being introduced into the fluidized bed thermal boiler (1), and / or recirculating 19 038810 The flue gases contained in the above mixture are heated in a heat exchanger (34) to heat the recirculated flue gases by means of flue gases discharged from the fluidized bed heat boiler (1), before being introduced into the fluidized bed heat boiler. 17. The method according to claim 11, characterized in that the flue gases discharged from the thermal fluidized-bed boiler (1) are conducted into the first heat exchanger (27), where the aforementioned flue gases flow over the surface of at least one superheater (28, 29), in the form of a heat exchanger for generating superheated steam, and then on the surface of at least one heater (30) in the form of a heat exchanger for heating water and / or a mixture of steam and water supplied to the drum (31) to power the superheater (28, 29) with steam, after which the flue gases are passed into a second heat exchanger (32), where the aforementioned flue gases flow through at least one heat exchanger (36, 37) to heat the air, after which the flue gases are passed through a filter (40), and then part of the flue gases are passed into a pipeline for supplying a fluidizing medium to a heat boiler (1) with a fluidized bed and / or to at least one heat exchanger (35) to heat recirculation furnaces gas, from which the aforementioned part of the flue gases is led into a pipeline for supplying a fluidizing medium to a fluidized-bed heat boiler (1), the said pipeline being provided with an inlet into which air is fed after passing through the aforementioned heat exchanger (37) to heat the air, or the aforementioned flue gases flow over the surface of at least one heat exchanger to generate steam, and then over the surface of at least one heater (30) in the form of a heat exchanger for heating water and / or a mixture of steam and water supplied to the drum (31), after which flue gases are led into a second heat exchanger (32), where the aforementioned flue gases flow through at least one heat exchanger (36, 37) to heat the air, after which the flue gases are passed through a filter (40), and then part of the flue gases are led into a pipeline for feeding a fluidizing medium into a heat boiler (1) with a fluidized bed and / or at least about dyn heat exchanger (35) for heating recirculated flue gases, from which the aforementioned part of the flue gases is led into a pipeline for supplying a fluidizing medium to a fluidized bed heat boiler (1), the said pipeline being provided with an inlet into which air is supplied after passing through the aforementioned heat exchanger ( 37) to heat the air, or the flue gases discharged from the thermal fluidized bed boiler (1) are passed over the surface of at least one heat exchanger to obtain warm water, after which the flue gases are passed to the second heat exchanger (32), where the above-mentioned furnace the gases flow through at least one heat exchanger for heating the recirculated flue gases and through at least one heat exchanger (36, 37) for heating the air, after which the flue gases are passed through the filter (40), and then part of the flue gases are passed into the pipeline for supply fluidizing medium into a thermal fluidized boiler (1) the above layer is provided with an inlet into which air is fed after passing through the above-mentioned heat exchanger (37) for heating the air. 18. A method according to claim 17, characterized in that the secondary air is introduced into the pipeline for supplying the combustion chamber with the secondary gas, the said pipeline is provided with an inlet into which the air is fed after passing through the aforementioned heat exchanger (36) for heating air or flue gas, which passed through the filter (40), and it is conducted into at least one heat exchanger (34, 35) for heating the recirculated flue gases.