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Title:
METHOD FOR COMBUSTIBLE MASS RECOVERY FROM BOTTOM ASH AND INSTALLATION FOR RECOVERY OF COMBUSTIBLE MASS FROM ASH
Document Type and Number:
WIPO Patent Application WO/2017/074201
Kind Code:
A1
Abstract:
The method for combustible mass recovery from bottom ash, primarily sourced from the burners of power boilers, that is stoker-fired, pulverized fuel or fluidized-bed boilers, especially those fired by fossil fuels, municipal, agricultural, animal or industrial waste or sludge is characterized in that the bottom ash with combustible mass and slag crushed to a size of less than 5 mm being screened through an array of sieves with gradually decreasing mesh sizes, while subsequent sieves are used to capture plus mesh of graining over 1000 μm, preferably over 800 μm and most preferably over 500 μm, which then constitutes the recovered combustible mass. The installation for the recovery of combustible mass from ash characterized in that it consists of multi-sieve vibrating screen (10) equipped with several screens, each mesh size in the range of 5000 μm to 500 μm, while the mesh size of the finest screen is in the range of 1000 to 500 μm and preferably 800 μm; moreover it has a chute connected through a feeder (9) with a fly ash storage area (8) and through another feeder (6) with a hopper of minus mesh of a vibrating screen (5) of a mesh size of 5000 μm to 2000 μm, a chute of which is connected through a feeder (4) with a hopper of the crusher (3), a chute of which is connected through a feeder (2) with a bottom ash storage area (1) and through another feeder (7) with a hopper of plus mesh of vibrating screen (5).

Inventors:
KARCZ, Henryk (ul. Dworska 10, 95-015 Głowno, PL)
BUTMANKlEWICZ, Tomasz (ul. Rzeszowska 26/5, 45-316 Opole, PL)
Application Number:
PL2016/000051
Publication Date:
May 04, 2017
Filing Date:
May 09, 2016
Export Citation:
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Assignee:
KARCZ, Henryk (ul. Dworska 10, 95-015 Głowno, PL)
International Classes:
F23B70/00; B03B9/04; B07B1/28; F23J3/06; F24B15/00
Domestic Patent References:
2015-07-02
Foreign References:
EP2301683A22011-03-30
US20150258552A12015-09-17
US5775237A1998-07-07
JP2001276568A2001-10-09
PL203253A11978-07-17
Attorney, Agent or Firm:
SZELWIGA, Tomasz (Kancelaria Patentowa iPAT, ul. Sanocka 1/14, 53-304 Wrocław, PL)
Download PDF:
Claims:
Patent claims

1. The method of recovering combustible mass from bottom ash is distinctive by the bottom ash with combustible mass and slag crushed to a size of less than 5 mm being screened through an array of sieves with gradually decreasing mesh sizes, while subsequent sieves are used to capture plus mesh of graining over 1000 μm, preferably over 800 μm and most preferably over 500 μm, which then constitutes the recovered combustible mass.

2. The method according to claim 1 is distinctive by the bottom ash being crushed to a grain size of less than 2 mm.

3. The method according to claim 1 is distinctive by each sieve in the array of sieves with gradually decreasing mesh sizes having a mesh size range between 5000 μm and 500 μm, with the plus mesh of each sieve forming the recovered combustible mass.

4. The method according to claim 1 or 3 is distinctive by the finest sieve of the array of sieves with gradually decreasing mesh sizes having a mesh size between 1000 μm and 500 μm, preferably 800 μm.

5. The method according to claim 1, 3 or 4 is distinctive by the array of sieves with gradually decreasing mesh sizes including two or three sieves with a mesh size range between 1500 μm and 500 μm, while the mesh size difference between the sieves is between 200 μm and 500 μm, with the plus mesh of each sieve forming the recovered combustible mass.

6. The method according to claim 1, 3 or 4 is distinctive by the array of sieves with gradually decreasing mesh sizes including three sieves with a mesh size range between 2000 μm and 500 μm, while the mesh size difference between sieves is at least 200 μm, preferably the mesh size is 1500 μm for the first sieve, 1000 μm for the second sieve, 800 μm or 500 μm for the third sieve, with the plus mesh of each sieve forming the recovered combustible mass.

7. The method according to claim 1, 3 or 4 is distinctive by the array of sieves with gradually decreasing mesh sizes including four sieves with a mesh size range between 3000 μm and 500 μm, while the mesh size difference between sieves is at least 200 μm, preferably the mesh size is 3000 μτα for the first sieve, 2000 μm for the second sieve, 1000 μm for the third sieve, 800 μηι or 500 μm for the fourth sieve, with the plus mesh of each sieve forming the recovered combustible mass.

8. The method according to claim 1, 3 or 4 is distinctive by the array of sieves with gradually decreasing mesh sizes consisting of sieves with the mesh sizes of SOOO μm, 3000 μm, 2000 μm, 1000 μm and the last, finest sieve with the mesh size in the range from 900 μm to 500 μm, preferably 800 μm, with the plus mesh of each sieve forming the recovered combustible mass.

9. The method according to claim 1 or 2 is distinctive by bottom ash of a size of less than 5 mm, preferably less than 2 mm, being crushed in crusher (3), and before it is fed to the multi-sieve array with gradually decreasing mesh sizes it is screened in the sieve vibrating screen (5) with a mesh size between 5000 μm and 2000 μm, while the minus mesh of that sieve vibrating screen (5) is the bottom ash fed to the array of sieves with gradually decreasing mesh sizes.

10. The method according to claim 9 is distinctive by the plus mesh of the sieve vibrating screen (5) being again fed for crushing to a size of less than 5 mm, preferably less than 2 mm, in crusher (3).

11. The method according to claim 1, 3, 4, 5, 6, 7 or 8 is distinctive by the fly ash containing combustible mass, alternately with the bottom ash, being screened in the array of sieves with gradually decreasing mesh sizes, while the plus mesh separated at each sieve, of more than 1000 μm, preferably more than 800 μm and most preferably more than 500 μm, is the combustible mass recovered from that fly ash.

12. The method according to claim 1 is distinctive due to the fact that minus mesh from the array of several screens of a gradually decreasing mesh size is passed to ash storage area (13) or is passed after milling in the grinding mill (15) to the particle size below 0.5 mm to vibrating screen (16) of the mesh size of the finest screen in range of 250 to 80 μm, preferably 200 μm, from which minus mesh is directed to a dusty ash storage area (17) and plus mesh to a low calorific value combustible mass storage area (19).

13. The method according to claim 1 is distinctive due to the fact that plus mesh containing recovered combustible mass from subsequent screens of the array of several screens of a gradually decreasing mesh size is taken to a high calorific value combustible mass storage area (22).

14. The installation for the recovery of combustible mass from ash characterized in that it consists of multi-sieve vibrating screen (10) equipped with several screens, each mesh size in the range of 5000 urn to 500 μm, while the mesh size of the finest screen is in the range of 1000 to 500 μm and preferably 800 μm; moreover it has a chute connected through a feeder (9) with a fly ash storage area (8) and through another feeder (6) with a hopper of minus mesh of a vibrating screen (5) of a mesh size of 5000 μm to 2000 μm, a chute of which is connected through a feeder (4) with a hopper of the crusher (3), a chute of which is connected through a feeder (2) with a bottom ash storage area (1) and through another feeder (7) with a hopper of plus mesh of vibrating screen (5).

15. The installation according to claim 14 characterized in that a hopper of plus mesh of multi-sieve vibrating screen (10) is connecting through a feeder (24) with a high calorific value combustible mass tray (20) and then through another feeder (21) with high calorific value combustible mass storage area (22), while a hopper of minus mesh is connected through a feeder (12) with an ash storage area (13) and through a subsequent feeder (14) with a grinding mill (15) connected through a feeder (23) with a vibrating screen (16) with the finest screen mesh size in the range 250 to 80 μm, preferably 200 μm, whose a plus mesh hopper is connected through a feeder (18) with a low calorific value combustible mass storage area (19), while a hopper of minus mesh is connected through a feeder (25) with dusty ash storage area (17).

16. The installation according to claim 14 characterized in that multi-sieve vibrating screen (10) is equipped with an array of five screens with mesh sizes equal to 5000, 3000 , 2000, 1000 and 800 μm or 500 μm.

17. The installation according to claim 15 characterized in that multi-sieve vibrating screen (1 ) is equipped with an array of three screens with mesh sizes equal to 500, 200, 100 or two screens with mesh size equal to 500 μm and 200 μm.

18. The installation according to claim 15 characterized in that a high calorific value combustible mass storage area (22) is connected through a feeder (26) with a briquetting or pelletizing device (27).

19. The installation according to claim 15 characterized in that a high calorific value combustible mass storage area (22) is connected through a feeder (28) with equipment for activated carbon production (29).

20. The installation according to claim 15 characterized in that a high calorific value combustible mass storage area (22) is connected through a feeder (30) with a coal dust mill (31) connected with a nozzle burner (32) and a powdered-fuel burner (33) of a power boiler (37).

21. The installation according to claim IS characterized in that a low calorific value combustible mass storage area (19) and a high calorific value combustible mass storage area (22) are interconnected through associated feeders (34, 35) with a coal dust mill (36) connected with a powdered-fuel burner (33) of a power boiler (37).

Description:
Method for combustible mass recovery from bottom ash and installation for recovery of combustible mass from ash

The subject of the invention is a method for combustible mass recovery from bottom ash, primarily sourced from the burners of power boilers, that is stoker-fired, pulverized fuel or fluidized-bed boilers, especially those fired by fossil fuels, municipal, agricultural, animal or industrial waste or sludge, plus a description of the installation for its execution. The subject of the invention also solves the recovery of combustible mass from fly ash. The subject of the invention also presents examples of possible use of recovered combustible mass.

There are many known methods for coke breeze recovery from fly ash. The Polish description of the invention PL 203253 describes a method for utilization of products of incomplete lignite combustion in a power boiler and an installation for the execution of this method. The method described by the above invention consists in that all solid furnace waste containing a certain amount of coke breeze are taken by means of hydraulic transport from the power boiler and boiler equipment to the pumping station tank containing water as a flotation liquid. In the pumping station tank, a mixture of water, slag, ash and coke breeze is aerated with air from the collector located in the flotation liquid. The collector nozzles' jet is directed towards the bottom of the tank. After the flotation process, ash and slag sediment is removed from the bottom of the tank using a slurry pump, while the coke breeze left on the liquid's surface is raked up by water jets from water nozzles to the corner of the pumping station tank, from where it is transported using a bucket conveyor to a container, where it is filtered off. According to the above invention, the installation contains a tank equipped with a collector with nozzles providing aeration and mixing flotation liquid with slag, ash and coke breeze. There are rails mounted along the tank's wall, using which the carriage moves the water collector with a system of nozzles that rake up - with water jets - layers of coke breeze from the surface of the flotation liquid towards the wall and using an additional nozzle, to the comer, from which coke breeze is taken using a bucket conveyor to the settler near the feeder. Slurry pumps are installed near the bottom of the tank to evacuate slag and ash.

The Polish invention P.396657 describes a method of recovery of combustible mass from fly ash and equipment for the execution of this method. The method consists in that fly ash separated from flue gases containing combustible material is brought by an air jet to the fluidised-bed reactor and poured down the reactor by its side surface, where the fly ash is sucked in by the fluidised bed formed in the middle part of the reactor and supplied with a directed upwards stream of fluidising gas. The ash blown away from the bed and separated from the combustible mass in the fluidisation process is taken through an ash drain located near the central part of the reactor, while the combustible mass blown away from the bed and detached in the fluidisation process is taken through the combustible mass drain located in the upper part of the reactor, near the cover, and fluidising gas is evacuated to an outlet throat, the inlet of which is located below the upper cover of the reactor and covered by a screen, preferably in the shape of a cone sleeve that stops direct discharge of fluidising gas from the reactor. The device is composed of a fluidised-bed reactor that in the upper cover has a fluidising air outlet throat, the inlet of which is embedded deep in the reactor and covered with a screen preferably in shape of a cone sleeve; in the upper part below the cover there is a drain for combustible mass separated from the ash in the fluidisation process, in the middle section a drain for ash separated from the combustible mass, at the bottom a shaped hopper enclosed with a nozzle bottom with a fluidising gas box, through which a fluidising gas stream is introduced; the stream is directed upwards and creates a fluidised bed from the ash with the combustible mass introduced into the reactor in the area around the vertical axis of the reactor; and located above the hopper an inlet of the ash and the combustible mass separated from flue gases.

The Polish invention P.403622 describes a method for recovery of coke breeze from fly ash that consists in fly ash being moved through the power boiler ash removal system to a vibrating screen sieve equipped with a set of screen sieves of the lowest mesh value of 500 μm, fraction of particles above 500 μm is directed to separated coke breeze collection system, while fly ash with the fraction of particles of a size below 500 μm is directed to the cylindrical fluidised bed reactor, where it is fluidised in a fluidised bed formed around the longitudinal axis of the cylindrical fluidised bed reactor, the fluidised bed is supplied with an upward fluidising gas stream introduced inside the reactor by a fluidising gas box mounted on the nozzle bottom that terminates the cylindrical fluidised bed reactor from below. Ash particles separated from the mixture of the fluidising gas stream and fly ash are taken from the cylindrical fluidised- bed reactor through ash discharge channels, located in the central part of the sleeve and in the bottom, to ash rinsing apparatus, while blown away and entrained breeze coke with fluidising gas is taken from the cylindrical fluidising reactor to the bag filter for treatment

The Polish invention P.403622 describes an installation for the recovery of breeze coke from fly ash comprised of a three-way manifold connected through a closing flap with an ash rinsing apparatus and through a closing flap with a vibrating screen sieve equipped with a set of sieves of the lowest mesh value of 500 μιη connected with a separated coke breeze collection system and cylindrical fluidised bed reactor that is terminated at the bottom with the nozzle bottom enclosed with a fluidising gas box connected with a fluidising gas fan, enclosed from the top with a roof, in which a fluidising gas outlet throat is located; the outlet throat is connected with a bag filter connected with a fluidising gas exhaust fan and with a separated coke breeze collection system; moreover, in the middle part of its sleeve and bottom it is equipped with ash drain channels connected through an ash transport channel with an ash rinsing apparatus.

The Polish invention P.407157 describes a method for recovery and use of coke breeze from furnace ash that consists in fly ash being moved to a vibrating screen sieve equipped with a set of sieves of the lowest mesh value of S00 μm, a fraction of particles above 500 μm separated from fly ash is directed to separated coke breeze tank, while fly ash with fraction of particles of a size below 500 μm is directed to the cylindrical fluidised bed reactor, where it is fluidised in the fluidised bed formed around the longitudinal axis of the cylindrical fluidised bed reactor; the fluidised bed is supplied with an upward fluidising gas stream introduced inside the reactor by a fluidising gas box mounted on the nozzle bottom that terminates cylindrical fluidised bed reactor from the bottom. Ash particles separated from the mixture of the fluidising gas stream and fly ash are taken from the cylindrical fluidised-bed reactor through ash discharge channels located in the central part of the sleeve and in the bottom to a particulate conveyor, while entrained breeze coke is taken from the cylindrical fluidising reactor using a carrier gas that enters the cylindrical fluidising reactor in its roof zone is taken for combustion in a set of burners or to the equipment separating solid particles from gas, from which it is subsequently taken to the separated coke breeze tank; fluidising gas from the cylindrical fluidised bed reactor is carried away using a fluidising gas connector pipe embedded in the cylindrical fluidised bed reactor with the inlet covered with a screen to the power boiler flue gas channel or through a dust separator to the atmosphere, coke breeze from the separated coke breeze tank is carried outside the installation or transported to the mill array and then after milling to a set of burners, or to a comminution device and after comminution to a liquid fluidised bed reactor, from where it is subsequently moved to a milling assembly and, after comminution, to be burned in a set of burners or to be burned in a power boiler furnace.

The Polish invention P.407157 describes an installation for the recovery of breeze coke from fly ash comprised of a three-way manifold connected through a closing flap with a particulate conveyor and through a closing flap with a vibrating screen sieve equipped with a set of sieves of the lowest mesh value of 500 μιη connected with a separated coke breeze collection system and a cylindrical fluidised bed reactor mat is terminated at the bottom with the nozzle bottom terminated with a fluidising gas box connected with a fluidising gas fan, the cylindrical fluidised bed reactor is equipped with ash drain channels in its mid side wall and in the bottom connected with a particulate conveyor, while the cylindrical fluidised-bed reactor is enclosed with a roof, in which an embedded fluidising gas pipe with the inlet screen is located, connected through a channel with a power boiler flue gas channel equipped with a dust separator and a channel with a dust separator. Moreover, in the top zone there is an inlet port equipped with carrier gas guide vanes and connected to the fan and coke breeze outlet port connected through a channel with a burner assembly and through a channel with a p articulate-gas separator connected with a flue gas channel, dust separator and with a separated breeze coke tank, which is connected with a milling assembly connected with a power boiler burner set that is connected through a slag drain channel with a particulate comminution device connected with a liquid fluidised-bed reactor that is connected with a three-way manifold, a power boiler furnace and a milling assembly.

However, there are no known methods of recovery of combustible mass from bottom ash. As a rule, bottom ash containing mass percentage of combustible mass in a range from several to over 30% is directed to a dump.

The essential object of the invention is to solve problem of the recovery of combustible mass from bottom ash. Due to the fact that in power plants there is also a need to recover combustible mass from fly ash, the solution described in the invention also includes this process, and moreover, presents a method for the use of the obtained combustible mass. A characteristic of the method of recovering combustible mass from bottom ash according to the invention is that bottom ash with combustible mass and slag crushed to a size of less man 5 mm, and preferably less than 2 mm, is screened through an array of sieves of gradually decreasing mesh sizes, while subsequent sieves are used to capture plus mesh of graining over 1000 μm, preferably over 800 μm and most preferably over 500 μm, which then constitutes the recovered combustible mass. Each sieve in the array of sieves with gradually decreasing mesh sizes has a mesh size range between 5000 μm and 500 μm, with the plus mesh of each sieve being the recovered combustible mass.

Preferably, the smallest sieve in the array of sieves with gradually decreasing mesh sizes has a mesh size between 1000 μm and 500 μm, preferably 800 μm.

Preferably, the array of sieves with gradually decreasing mesh constitute sieves of one multi-sieve vibrating screen.

Preferably, the array of sieves with gradually decreasing mesh sizes includes two or three sieves with a mesh size range between 1500 μm and 500 μm, while the mesh size difference between the sieves is between 200 μm and 500 μm, with the plus mesh of each sieve forming the recovered combustible mass.

Preferably, the array of sieves with gradually decreasing mesh sizes includes three sieves with a mesh size range between 2000 μm and 500 μm, while the mesh size difference between sieves is at least 200 μm, preferably the mesh size is 1 00 μm for the first sieve, 1000 μm for the second sieve, 800 μm or 500 μm for the third sieve, with the plus mesh of each sieve forming the recovered combustible mass.

Preferably, the array of sieves with gradually decreasing mesh sizes includes four sieves with a mesh size range between 3000 μm and 500 μm, where the mesh size difference between the sieves is at least 200 μm, preferably the mesh size is 3000 μm for the first sieve, 2000 μm for the second sieve, 1000 μm for the third sieve and 800 μm or 500 μm for the fourth sieve, with the plus mesh of each sieve forming the recovered combustible mass.

Preferably, the array of sieves with gradually decreasing mesh sizes consists of sieves with the mesh sizes of 5000 μm, 3000 μm, 2000 μm, 1000 μm and the finest sieve with the mesh size in the range between 900 μm and 500 μm, preferably 800 μm, with the plus mesh of each sieve forming the recovered combustible mass.

Preferably, bottom ash is comminuted to a particle size below 5 mm, preferably below 2 mm, in the crusher, while before passing it to the array of several screens with a gradually decreasing mesh size it is screened using a vibrating screen with a mesh size of 5000 μm to 2000 μm, while only minus mesh from this vibrating screen is supplied as a bottom ash to the array of several screens with a gradually decreasing mesh size. A plus mesh from this vibrating screen is redirected for comminution to a particle size below 5 mm, preferably below 2 mm, in the crusher.

Preferably, alternately with bottom ash on the array of several screens of a gradually decreasing mesh size is screened fly ash containing combustible mass with plus mesh of these screens contains recovered combustible mass.

Preferably, a minus mesh from the array of several screens of a gradually decreasing mesh size is passed to an ash storage area or, after comminution to a particle size below 0.5 mm in the regrinding mill, to a vibrating screen of the mesh size of the finest screen in a range of 250 to 80 urn, preferably 200 μm, from which minus mesh is directed to a dusty ash storage area and plus mesh to a low calorific value combustible mass storage area.

Preferably, plus mesh containing recovered combustible mass from subsequent screens of the array of several screens of a gradually decreasing mesh size is taken to high calorific value combustible mass storage area.

The installation for the recovery of combustible mass from ash is characterized in that it consists of a multi-sieve vibrating screen equipped with several screens, each of mesh size in the range of 5000 μm to 500 μm, while the mesh size of the finest screen is in range of 900 μm to 500 μm and preferably 800 μm; moreover, it has a chute connected through a feeder with a fly ash storage area and through another feeder with a hopper of minus mesh of the vibrating screen of mesh size of 5000 μm to 2000 μm, in turn its chute is connected through a feeder with a hopper of a crusher with a chute connected through a feeder with a bottom ash storage area and through another feeder with a hopper of plus mesh of the vibrating screen.

Preferably, a multi-sieve vibrating screen is equipped with an array of five screens of mesh sizes equal to 5000, 3000, 2000, 1000 and 800 μm.

Preferably, the hopper of plus mesh of a multi-sieve vibrating screen is connected through a feeder with a high calorific value combustible mass tray and then through another feeder with a high calorific value combustible mass storage area, while a hopper of minus mesh is connected through a feeder with an ash storage area and through a subsequent feeder with the regrinding mill connected through the feeder with a vibrating screen with the finest screen mesh size in the range from 250 to 80 μm, preferably 200 μm, plus the mesh hopper which is connected through a feeder with a low calorific value combustible mass storage area, while a hopper of minus mesh is connected through a feeder with a dusty ash storage area, while preferably the above vibrating screen is equipped with an array of three screens of mesh size 500, 200, 100 μm or of two screens of mesh size 500 μm, 200 μιη.

Preferably, the high calorific value combustible mass storage area is connected through a feeder with a briquetting or pelletizing device.

Preferably, the high calorific value combustible mass storage area is connected through a feeder with a device for production of activated carbon.

Preferably, the high calorific value combustible mass storage area is connected through a feeder with a coal dust mill connected with a nozzle burner and a powdered- fuel burner of the power boiler.

Preferably, the low calorific value combustible mass storage area and the high calorific value combustible mass storage area are connected through associated feeders with a coal dust mill connected with a powdered-fuel burner of the power boiler.

The advantage of the solution according to the invention is the use of the difference in biochar size distribution and slag size distribution in the crushed bottom ash for the recovery of combustible mass from bottom ash. Similarly, the subject invention uses the difference in the size distribution of the fly ash components.

The subject of the invention is shown in the drawing, in which fig. 1 presents the combustible mass recovery-and-use installation diagram, and fig. 2 presents an example slag and biochar size distribution.

The method of recovering combustible mass from bottom ash in the first embodiment according to the invention, is that the bottom ash deposited on bottom ash storage area 1 from the combustion of fossil fuels, deposits, waste or biomass, in the form of slag with biochar grains flooded inside - the combustible mass with a combustible mass weight percentage of generally up to 30% and granulation in the range from 10 mm to 100 mm is transported by feeder 2 to crusher 3, generally a roll crusher with a roll gap in the range of 2-4 mm, for example 3 mm, and with suitable pressure, that is the pressure applied by the rolls to crush the feed, in the range from 0.1 to 1 MPa, for example 0.6 MPa, in which the feed is crushed to a particle size of less than 5 mm. Bottom ash can also be crushed to obtain a particle size below 4, below 3, or below 2 mm. During the crushing process, due to different hardness and different brittleness of slag and char particles, slag is relatively easily separated from the char particles. The greater the comminution, the lower the content of carbonaceous substance - char is occluded in the slag particles. Consequently, for example during comminution of bottom ash to a particle size below 2 mm, the residue of char occluded in the slag particles is essentially below 5% mass content, whereas during comminution of bottom ash to a particle size below 5 mm, the residue of char occluded in the slag particles is essentially below 10% mass content. Bottom ash crushed in crusher 3, which constitutes a mixture of particles of slag and char, is transported with feeder 4 to vibrating screen S equipped with one screen of mesh size 5000 μm. Preferably, the vibrating screen 5 has a screen in the range of 5000 to 2000 μm. The plus mesh herein separated is transported by feeder 7 to be crushed again in crusher 3, while minus mesh is transported by feeder 6 to the array of several screens of a gradually decreasing mesh size. The result of crushing in crusher 3 and screening through the above-mentioned screen 5, depending on the size of the sieve used, is a bottom ash fraction in the range from 5 mm to less than 50 μm or, for example, from 2 mm to less than 50 μm. In this embodiment the array of several screens with a gradually decreasing mesh size is located within one multi-sieve vibrating screen 10 equipped with screens of mesh size 5000, 3000, 2000, 1000 and 800 μm, with the finest screen preferably having a mesh size in range of 900 μm to 500 μm. The embodiment of the method as described the invention may as well include subsequent screens of the array of several screens with a gradually decreasing mesh size placed in a few vibrating screens connected through ash conveyors. Moreover, the process of combustible mass recovery in the form of plus mesh can be conducted for many combinations, different from the above, of the nμmber of screens with mesh sizes in the range of 5000 to 500 μm. The application of the specific combination of the array of screens has an impact on the selection of adequate efficiency, but not the possibility of conducting the separation process itself. The mixture of slag and char particles passed on to an array of several vibrating screens of a gradually decreasing mesh size is fractioned into slag particles, including particles of a dominating mass content of slag and char particles, including particles of a dominating mass content of char, as due to higher brittleness and fragility after crushing the bottom ash in crusher 3, the particle diameter of slag is much lower than the char particle diameter. Particles of crushed slag are of a more regular shape, close to spherical, while char particles are irregular, close to plates of a highly developed flocculent structure. Across the size distribution of the slag in the bottom ash, the weight percentage is more than 90% for the fraction measuring less than 500 μm and more than 95% for the f action measuring less man 800 μm. Whereas, the size distribution of biochar in the bottom ash is such that the weight percentage is more than 80% for the fraction of more than 800 μm and more than 90% for the fraction of more than 500 urn. Fig. 2 of the drawing presents an example diagram that shows the weight percentage of slag and biochar grain fraction: the size distribution, obtained by use embodiment according to the invention. The separation of biochar (the combustible mass) from slag, graded in the array of sieves, prevents the occurrence of factors that restrict the flow of bottom ash from the sieve decks, in which additional assistance is given by the chains suspended over the sieves to flick the mixture of slag grains and biochar being fed. Mesh size gradation and additional stroke from loosely hanging chains causes large char particles of a flocculent external structure agglomerated in larger aggregates to be more easily broken down and removed from the surface of screens. The vibrating and reciprocating movement of screens of multi-sieve vibrating screen 10 is designed to loosen and break up adhered and aggregated particles of char and slag, while the screen hitting the loosely hanging chain during the periodic move of the screen upwards is to break up the aggregate and shake it through the mesh. Plus mesh containing recovered combustible mass, separated gradually on subsequent screens of the array of several screens of a gradually decreasing mesh size in multi-sieve vibrating screen 10, in the form of particles that did not pass through the finest screen of the array of screens of mesh size 800 μm is transported using feeder 24 to the high calorific value combustible mass tray 20, from which it is transported to the high calorific value storage area 22 with the use of feeder 21. Preferably, plus mesh containing recovered combustible mass from individual screens in the high calorific value combustible mass tray 20 is fed into respective chamber 11. Minus mesh of particle sizes passing through all subsequent screens of the array of several screens of a gradually decreasing mesh size, including the screen of the finest mesh size 800 μm is directed from the array of vibrating screens of a gradually decreasing mesh size within the multi-sieve vibrating screen 10 using feeder 12 to ash storage area 13. In this case, the recovered combustible mass is contained in the plus mesh from screens of mesh sizes equal to 5000, 3000, 2000, 1000 and 800 μm. While screening the bottom ash through the array of the above-mentioned sieves, it is possible to recover more than 80% of the combustible mass (biochar mass) from the bottom ash and, due to the difference between the size distribution of the slag contained in the bottom ash and the size distribution of the biochar, the weight percentage of slag in the plus mesh (the recovered combustible mass) will be of the order of several percent. However, when the bottom ash is screened through an array of the above- mentioned five sieves, with the finest sieve mesh size of 500 μm, the recovery of the combustible mass in the bottom ash can increase to more than 90%, while also increasing by several percent the percentage of slag in the plus mesh: the recovered combustible mass. When the bottom ash is screened through an array of two sieves, in which the mesh size is 1500 urn for the first sieve and 1000 μm for the second sieve, it is possible to recover f om 50 to 70% of the combustible mass from the bottom ash in the form of plus mesh at each sieve. However, when screening the bottom ash through an array of sieves consisting of three sieves, in which the mesh size is 1500 μm for the first sieve, 1000 urn for the second sieve and 800 μm for the third sieve, it is possible to recover more than 70% of the combustible mass from the bottom ash in the form of plus mesh at each sieve, and while using the finest sieve with a mesh size of 500 μm, it is possible to recover up to 90% of the combustible mass from the bottom ash. As already indicated above, adding more sieves with larger mesh sizes to the above-mentioned sieve configurations, namely 2000 μm, 3000 μm, 4000 μm or 5000 μm, generally helps to improve the separation process. The compressive strength of the bottom ash - primary slag is generally in the range of 0.1 to 1 MPa; therefore, the parameters of crusher 3, including in particular the gap size and suitable pressure, are selected so that the slag fraction of less than 500 μm has the highest possible share in the general slag weight and the combustible mass f action of less than 500 μm or 800 um has the lowest possible share in the general combustible mass weight The size/mesh size of each sieve is understood as the length of one side of a square-shaped aperture. The graining below/above the given size is understood as plus mesh/minus mesh from the square- shaped aperture sieve of the same given size.

The method for recovery of combustible mass from bottom ash in the second embodiment according to the invention is consistent with the first embodiment in the scope of recovery of combustible mass from bottom ash, while it includes also the recovery of combustible mass from fly ash, and moreover presents a method for using combustible mass obtained from bottom ash and fly ash. Consequently, there is a difference in that fly ash of combustible mass content at the level of up to 20% being a mixture of ash and coke breeze is transported also by feeder 9 directly from the fly ash storage area 8 to the array of several screens with a gradually decreasing mesh size located within one multi-sieve vibrating screen 10. It is preferable if a stream of fly ash to the array of several screens with gradually decreasing mesh size within the multi- sieve vibrating screen 10 is fed alternately and separately with bottom ash stream. Separate and alternate feeding streams are dictated by the different structure of slag and char particles contained in bottom ash from ash and coke breeze particles contained in fly ash. Bottom ash has char occluded inside slag aggregates. The crushed particles contained in bottom ash have a geometrical structure of rough walls and numerous flocks, which partially block the flow of particles through vibrating screens. For fly ash, ash particles have a more regular, spherical structure of a smoother surface that enables easier passing of ash particles through the mesh, thus preventing the screen's surface from becoming blocked by particles stuck on the mesh. In fly ash, coke breeze particles are not aggregated with ash particles as char and slag particles in bottom ash. Coke breeze particles in principle have the shape of plaques and various polyhedrons with a developed rough surface. Supplying separately crushed slag containing char and ash containing coke breeze to the array of several screens of gradually decreasing mesh sizes of multi-sieve vibrating screen 10 provides a much better separation process of fly ash than in simultaneous feeding of both ash streams. Moreover, when feeding bottom ash the applied vibration amplitude is higher than for fly ash. When fractioning bottom ash, the applied vibration amplitude is in range from 5 to 10 mm, while for f actioning fly ash it is from 5 to 8 mm. In the size distribution of ash in the fly ash, the weight percentage is more than 80% for the fraction of less than 500 urn and more than 90% for the fraction of less than 800 μm. Whereas, the size distribution of coke breeze in fly ash is such that the weight percentage is more than 80% for the fraction of more than 800 μm and more than 90% for the fraction of more than 500 μm. The bottom ash and fly ash plus mesh, consisting of the grain sizes captured by a sieve with a mesh size of 800 μm with the weight percentage of combustible mass, are carried from multi-sieve vibrating screen 10 by feeder 24 to high-calorific value combustible mass fraction tray 20, from which they are carried by feeder 21 to high-calorific value combustible mass storage area 22. The minus mesh separated in multi-sieve vibrating screen 10, consisting of bottom ash and fly ash with sizes resulting from passing through sieve with a mesh size of 800 μm, is carried partly by feeder 12 directly to ash storage area 13 and partly by feeder 14 to grinding mill 15, which grinds the ash fed with the combustible mass to sizes of less than 0.5 mm to obtain ash for chemical purposes and for the production of different types of construction mortars and adhesives. The ash and combustible input ground in grinding mill 15 is carried by feeder 23 to sieve vibrating screen 16, which is equipped with three sieves with mesh sizes of 500 μm, 200 μm and 100 μm. Preferably, sieve vibrating screen 16 is equipped with two sizes of sieves: 500 μm and 200 μm. The plus mesh with the grain size of more than 100 μm or more than 200 μm separated at sieve vibrating screen 16 is carried by feeder 18 to low-calorie combustible mass storage area 19, while minus mesh ash with sizes of less than 100 urn or 200 urn is fed by feeder 25 to dusty ash storage area 17. When screening through the above-mentioned sieve vibrating screen 16, further combustible mass recovery f om the bottom ash or fly ash of approx. 5- 5% of the combustible mass weight percentage in the ash is possible; however the slag and/or fly ash will constitute a relatively high, more than 70% by weight, percentage in the recovered combustible mass. High calorific value combustible mass from a high calorific value combustible mass storage area 22 is transported with feeder 26 to briquetting and pelleting device 27, where it is used for production of high calorific value smokeless fuel that is used mainly in public utility institutions. High calorific value combustible mass is also transported with feeder 28 to equipment for activated carbon production 29, which is used for adsorption of gaseous and liquid substances. Moreover, high calorific value combustible mass is also transported with feeder 30 to coal dust mill 31 that produces dust combusted in separate burner nozzle 32 or together with coal dust in powdered-fuel burner 33 of power boiler 37. Low calorific value combustible mass stored in the low calorific value storage area 19 after previous milling to dust in coal dust mill 36 can be burned individually or co-burned with a coal milled at the same time in coal dust mill 36 in powdered-fuel burner 33 of power boiler 37. High calorific value combustible mass from the high calorific value combustible mass storage area 22 is fed using feeder 34 to coal mill 36 and can be co-fired with coal dust from other sources in powdered-fuel burner 33 of power boiler 37.

The installation for the recovery of combustible mass from ash in the embodiment according to the invention is constructed from a bottom ash storage area 1 connected through a feeder 2 with chute of crusher 3, hopper of which through feeder 4 is connected with a chute of vibrating screen 5, plus mesh hopper of which is connected through feeder 7 with chute of crusher 3, while minus mesh hopper through feeder 6 is connected with chute of multi-sieve vibrating screen 10. Chute of multi-sieve vibrating screen 10 is additionally connected through feeder 9 with fly ash storage area 8. Vibrating screen 5 is a vibrating single-sieve screen of a mesh size equal to 5000 μm, while above the screen sieve it has a metal chain hanging loosely from the top of the screen at the distance of half the stroke of vibration amplitude of screen at rest Preferably, the vibrating screen 5 has a screen of mesh size in range from 5000 to 2000 μm. Multi-sieve vibrating screen 10 is equipped with five screens of mesh sizes equal to 5000, 3000, 2000, 1000 and 800 μm, while preferably mesh size of the finest screen is in the range of 900 to 500 μm. The multi-sieve vibrating screen 10 has above each screen sieve a metal chain hanging loosely from the top of the screen at the distance of half the stroke of vibration amplitude of screen at rest A hopper of minus mesh of multi-sieve vibrating screen 10 is connected through feeder 12 with ash storage area 13, and through feeder 14 - with a chute of the grinding mill 15, its hopper is connected through feeder 23 with chute of sieve vibrating screen 16, a minus mesh hopper of which is connected through feeder 25 with dusty ash storage area 17, while its plus mesh hopper is connected through feeder 18 with low calorific value combustible mass storage area 19. Vibrating screen 16 is equipped with three screens of mesh sizes equal to 500, 200 and 100 μm, while preferably mesh size of the finest screen is in the range of 150 to 80 μm. Vibrating screen 16 can also have two screens with mesh sizes equal to 500 and 200 μm, while in this case preferably the mesh size of the finest screen is in range of 250 to 150 μm. Vibrating screen 16 has above each screen sieve a metal chain loosely hanging from the top of the screen at the distance of half the stroke of vibration amplitude of screen at rest. The plus mesh chute of the multi-sieve vibrating screen 0 is connected through feeder 24 with the high calorific value combustible mass tray 20, which is then connected through feeder 21 with high calorific value combustible mass storage area 22. High calorific value combustible mass tray 20 is divided into fraction chambers 11. Preferably, high calorific value combustible mass storage area 22 is connected through feeder 26 with briquetting or pelletizing device 27, while through feeder 28 with equipment for activated carbon production 29. Moreover, high calorific value combustible mass storage area 22 is connected through feeder 30 with coal dust mill 31 connected with nozzle burner 32 and powdered-fuel burner 33 of power boiler 37. Moreover, the low calorific value combustible mass storage area 19 and the high calorific value combustible mass storage area 22 are interconnected through associated feeders 34, 35 with coal dust mill 36 connected with a powdered-fuel burner 33 of a power boiler 37.