SI21862A

SI21862A - Ring shaft kiln for firing lime with recirculation of kiln gases

Info

Publication number: SI21862A
Application number: SI200500280A
Authority: SI
Inventors: Andrej Senegacnik; Janez Oman; Brane Sirok
Original assignee: Andrej Senegacnik
Priority date: 2005-10-05
Filing date: 2005-10-05
Publication date: 2006-02-28

Abstract

A ring shaft kiln for firing lime with recirculation of kiln gases is carried out in the manner to have a gas recirculation channel between an exit gas channel (21) from a recuperator (3) and a secondary air feeding pipes leading to lower (7) and upper (15) burners. A blower (22) enables the flow of recirculation gases over control flaps (23) and mixing chambers (24) to the lower (7) and upper (15) burners. Recirculation gases are taken from the exit gas channel (21) on the place of their highest temperature directly at the exit from the recuperator (3). All recirculation components are thermally insulated so that their surface temperature does not exceed 40 degrees Celsius.

Description

OBROČNA JAŠKASTA PEČ ZA ŽGANJE APNA Z RECIRKULACIJO PLINOV IZ PEČIORIGINAL COVERED LAMP HEATING OVEN WITH RECIRCULATION OF GASES FROM OVEN

Predmet izuma je naprava - obročna jaškasta peč za žganje apna z recirkulacijo plinov iz peči. Izum sodi na področje strojništva - termoenergetike, tehnološke peči.The object of the invention is a device - a ring shaft furnace for calcining lime with the recirculation of the gases from the furnace. The invention belongs to the field of mechanical engineering - thermal power engineering, technological furnaces.

Izum obravnava predelavo obročne jaškaste peči za žganje apna, kjer z recirkulacijo odpadnih plinov iz peči izboljšamo skupni izkoristek peči. Tehnični problem, ki ga rešuje izum z recirkulacijo odpadnih plinov iz peči, je nižanje razmernika zraka za zgorevanje, ter sočasno zmanjševanje izgub s toploto odpadnih plinov, pri čemer temperature v gorilnih komorah ostajajo v okviru dopustnih.The invention relates to the processing of a ring shaft furnace for calcining lime, where the recirculation of waste gases from the furnace improves the overall efficiency of the furnace. A technical problem solved by the invention by the recirculation of the exhaust gases from the furnace is the reduction of the combustion air ratio and the simultaneous reduction of the waste heat losses, while keeping the temperatures in the combustion chambers within acceptable limits.

V obstoječih obročnih jaškastih pečeh se ob znižanju razmernika zraka na vrednost, ki je optimalna za kurjenje goriva, temperature v gorilnih komorah povišajo preko dopustnih temperatur. Previsoke temperature v območju gorilnih komor povzročajo poškodbe v peči, nastajajo zlepki kamenja na stenah peči, nekateri kosi apna se prežgejo, kvaliteta apna je neenakomerna. Da temperature v gorilnih komorah ne presežejo dopustnih vrednosti, se pri današnjih postopkih plamen v gorilni komori hladi s sekundarnim zrakom, oziroma povečanim razmernikom zraka več kot je potrebno za dobro - optimalno zgorevanje. Pri večjem razmerniku zraka se temperatura v gorilni komori zniža, poveča se masni tok plinov v peči, s čemer se povečajo izgube s toploto odpadnih plinov na izstopu iz peči. To povečuje porabo goriva in niža izkoristek peči.In existing annular shaft furnaces, the temperatures in the combustion chambers are increased beyond the permissible temperatures as the air ratio is reduced to a value that is optimal for fuel burning. Too high temperatures in the area of the combustion chambers cause damage to the furnace, stumps of stones form on the walls of the furnace, some lime pieces burn, the quality of lime is uneven. In order that the temperatures in the combustion chambers do not exceed the permissible values, in today's processes the flame in the combustion chamber is cooled with secondary air, or increased air ratio more than is necessary for good - optimum combustion. At a larger air ratio, the temperature in the combustion chamber decreases, increasing the mass flow of the gases in the furnace, thereby increasing the heat losses of the exhaust gases at the exit of the furnace. This increases fuel consumption and reduces furnace efficiency.

Z uvedbo recirkulacije plinov iz peči - predložene tehnične rešitve, se predstavljeni problem uspešno rešuje. Izum omogoča doseganje dopustnih temperatur v gorilnih komorah, vendar ne s povečano količino zgorevalnega zraka. Posledica je povečanje toplotnega izkoristka peči in zmanjšanje porabe goriva. Princip recirkulacije plinov je ta, da plamen v gorilnih komorah hladimo z odpadnimi dimnimi plini, namesto s sekundarnim zrakom. Pogonski ventilator recirkulacije omogoči pretok in ponovno vpihavanje recirkuliranih plinov v gorilnike. Mešanje recirkuliranih plinov in sekundarnega zraka se izvede neposredno pred vpihom v gorilnike. Z regulacijskimi loputami je moče dosegati poljubna razmerja med recirkuliranimi plini in sekundarnim zrakom. Recirkulacija plinov omogoča naslednje:With the introduction of furnace gas recirculation - a technical solution presented, the presented problem is successfully solved. The invention allows to reach permissible temperatures in the combustion chambers, but not by increasing the amount of combustion air. The result is an increase in the thermal efficiency of the furnace and a decrease in fuel consumption. The principle of gas recirculation is that the flames in the combustion chambers are cooled by waste flue gas instead of secondary air. The recirculation drive fan allows the recirculated gases to flow and re-inject into the burners. Mixing of recirculated gases and secondary air is carried out immediately before being blown into the burners. The control flaps can be used to achieve arbitrary proportions between recirculated gases and secondary air. Gas recirculation enables the following:

• doseganje optimalnih razmernikov zraka za uporabljena goriva, zaradi česar se zmanjšajo toplotne izgube z odpadnimi plini iz peči, • odpadne pline za recirkulacijo lahko zajemamo na poljubnem mestu odvodnih kanalov, toda zaradi energijskih prihrankov je najbolje, da odpadne pline zajemamo na mestu, kjer imajo najvišjo temperaturo, to je na izstopu iz rekuperatorja, • poveča toplotni izkoristek peči, • niža temperature v gorilnih komorah, • možno doseganje povečane toplotne moči gorilnika pri nižji temperaturi plamena, • zaradi nižje koncentracije kisika v gorivni mešanici, se čas zgorevanja podaljša, lokalne toplotne obremenitve v gorilnih komorah se zmanjšajo,• achieving optimum air ratios for used fuels, thereby reducing heat losses from furnace gases; • recirculating waste gases can be captured at any point in the sewers, but for energy savings, it is best to capture the waste gases where they have maximum temperature, that is at the outlet of the recuperator, • increase the heat efficiency of the furnace, • lower temperature in the combustion chambers, • the possible achievement of increased thermal power of the burner at a lower flame temperature, • due to the lower oxygen concentration in the fuel mixture, the combustion time is extended, local the thermal loads in the combustion chambers are reduced,

Izum je uporaben na vseh tehnoloških pečeh, kjer z za kurjenje optimalnim razmernikom zraka, dosegamo previsoke temperature in jih nižamo z večanjm razmernika zraka, oz. namenoma hladimo plamen z zrakom.The invention is applicable to all technological furnaces, where by optimizing the air ratio for heating, high temperatures are reached and lower by increasing the air ratio, or. purposely cool the flame with air.

Izum bo opisan na izvedbenem primeru in skicah, ki prikazujejo:The invention will be described in the embodiment and in the drawings showing:

skica 1: Shema obročne jaškaste peči za žganje apna - dosedanje stanje skica 2: Shema peči z recirkulacijo plinov iz pečisketch 1: Schematic diagram of a ring shaft furnace for calcining lime - present situation sketch 2: Scheme of a furnace with recirculation of gas from the furnace

Opis tehnološke sheme obročne jaškaste peči za žganje apna - dosedanje stanjeDescription of the technological scheme of a ring shaft furnace for calcining lime - current status

Glavni element obročne jaškaste peči za žganje apna je vertikalna valjasta peč stolpne izvedbe 13, z notranjim valjem 16, spodnjimi gorilniki 7 in zgornjimi gorilniki 15. Apnenec 11 v granulirani kosovni obliki specifičnega premera 50 mm do 150 mm - surovina se dozira v peč na vrhu in se nato po peči pomika navzdol mimo gorilnikov 15 in 7, kjer zaradi visoke temperature med 900 °C in 1300 °C apnenec razpade v živo apno in ogljikov dioksid. Kosi živega apna 18 se na dnu odvajajo iz peči. Za vzdrževanje procesa žganja apna v peči so potrebne še nekatere naprave. Notranji valj 16 je prisilno hlajen z zrakom, ki ga dovaja ventilator 20. Hladilni zrak 17 se pri tem segreje in se zato dovaja v gorilnike 7 in 15 kot sekundarni zrak, odvečno količino 4 se izpušča v okolico. Del zgorevalnega zraka se v peč dovaja skozi plast že nastalega živega apna 19, ki ga ejektor 5 skupaj s pečnimi plini iz sotočne cone 8 posesa v notranji valj 16. Gonilni zrak 9 za ejektor 5 dovaja puhalo 10. Nasesani vroči recirkulirani plini se v ejektorju 5 zmešajo z gonilnim zrakom 6, nakar se uvajajo v spodnje gorilnike 7, kjer se dovede še gorivo in sekundarni zrak. Gorivo nato zgori v gorilni komori. Del nastalih dimnih plinov v spodnjih gorilnikih potuje navzdol po sotočni coni, del pa navzgor proti zgornjim gorilnikom 15, kjer se jim pridružijo še dimni plini iz zgornjih gorilnikov. Ko se temperatura dvigajočih plinov zniža pod 700 °C, lokacija 14, se del dvigajočih plinov odvede skozi glavo peči v rekuperator 3, kjer predgrevajo gonilni zrak 9. Ohlajeni plini 2 iz rekuperatorja se pred ventilatorjem vleka 1 ponovno združijo z ostalimi plini iz peči. Ventilator vleka 1 odvede odpadne pline iz peči v okolico. Glava peči 12 se prisilno hladi z zrakom, ki ga dovaja ventilator 20.The main element of the annular shaft furnace for calcining lime is a vertical cylindrical furnace of tower 13, with an internal cylinder 16, lower burners 7 and upper burners 15. Limestone 11 in granular piece shape with a specific diameter of 50 mm to 150 mm - the raw material is dosed into a furnace at the top and then moves down the furnace past burners 15 and 7, where due to the high temperature between 900 ° C and 1300 ° C, the limestone decomposes into living lime and carbon dioxide. Pieces of live lime 18 are drained from the furnace at the bottom. Some facilities are required to maintain the kiln lime burning process. The inner cylinder 16 is forcibly cooled by the air supplied by the fan 20. The cooling air 17 is thereby heated and thus fed to the burners 7 and 15 as secondary air, excess amount 4 being discharged into the surroundings. Part of the combustion air is fed into the furnace through a layer of already formed living lime 19, which is injected into the inner cylinder 16 by the ejector 5 together with the furnace gases from the confluent zone 8. The driving air 9 for the ejector 5 is supplied by a blower 10. The hot recirculated gases are fed into the ejector. 5 is mixed with the driving air 6, and then introduced into the lower burners 7, where fuel and secondary air are introduced. The fuel is then burned in the combustion chamber. Part of the flue gas generated in the lower burners travels down the confluence zone and part upwards towards the upper burners 15, where they are joined by the flue gas from the upper burners. When the temperature of the lifting gases drops below 700 ° C, location 14, part of the lifting gases is discharged through the furnace head to the recuperator 3, where the driving air is preheated 9. The cooled gases 2 from the recuperator are re-combined with the other gases from the furnace before the draft fan. Traction fan 1 draws waste gases from the furnace into the surroundings. The head of the furnace 12 is forcibly cooled by the air supplied by the fan 20.

Recirkulacija plinov - opis izuma, predelave pečiGas recirculation - description of the invention, furnace recovery

Obročna jaškasta peč za žganje apna z recirkulacijo plinov iz peči je predstavljena na skici 2. Recirkulacija plinov iz peči je izvedena tako, da se del izstopajočih plinov 2 iz rekuperatorja 3, po kanalu odvede v pogonski ventilator recirkulacije 22 in nato vodi po kanalu naprej proti mešalnim komoram 24, ki so nameščene na dovodnih vodih sekundarnega zraka spodnjih 7 in zgornjih gorilnikov 15. Za doseganje največjih možnih toplotnih prihrankov je pomembno, da se plini za recirkulacijo zajemajo na mestu 21, kjer imajo najvišjo temperaturo, to je neposredno na izstopu iz rekuperatorja. Seveda pa navedeno mesto odvzema plinov za recirkulacijo 21, takoj za rekuperatorjem, ne omejuje izuma obročne jaškaste peči z recirkulacijo plinov. Pline za recirkulacijo je mogoče po izumu odvzemati na poljubnem mestu kanala izstopajočih plinov, pri čemer bodo energijski prihranki zaradi nižjih temperatur recirkuliranih plinov nižji.The annular shaft furnace for calcining lime with the recirculation of the gases from the furnace is presented in Fig. 2. The recirculation of the gases from the furnace is carried out by removing a portion of the leaking gases 2 from the recuperator 3 through the duct into the recirculation drive fan 22 and then leading down the channel towards the duct. mixing chambers 24 mounted on the secondary inlet ducts of the lower 7 and upper burners 15. In order to achieve maximum thermal savings, it is important that the recirculation gases are captured at a location 21 where they have the highest temperature, i.e. directly at the outlet of the recuperator . Of course, the said recirculation gas recirculation site 21, immediately after the recuperator, does not limit the invention of the annular shaft furnace by gas recirculation. According to the invention, recirculation gases can be collected at any point of the exhaust gas channel, with lower energy savings due to lower recirculated gas temperatures.

V pogonskem ventilatorju recirkulacije 22 se tlak recirkuliranim plinom zviša nad nivo tlaka v gorilnikih. S tem je izpolnjen pogoj pretakanja in vpihavanja recirkulacijskih plinov v mešalne komore, ki so nameščene na dovodnih vodih sekundarnega zraka k spodnjim 7 in zgornjim gorilnikom 15. Regulacijske lopute 23 omogočajo doseganje primernega količinskega mešanja med sekundarnim zrakom in recirkuliranimi plini, kot tudi popolno izločitev/zaprtje sekundarnega zraka ali recirkulacijskih plinov pred gorilnikom. Recirkulacijski plini in sekundarni zrak se mešata v mešalni komori 24 neposredno pred vstopom v gorilnik. Količina recirkuliranih plinov, ki se pretaka skozi pogonski ventilator 22, se določa glede na sestavo recirkuliranih plinov vsebnost kisika in ogljikovega monoksida, ter glede na tehnološke zahteve temperatur v gorilnih komorah.In the recirculation drive fan 22, the pressure of the recirculated gas rises above the burner pressure level. This fulfills the condition of flowing and blowing the recirculating gases into the mixing chambers mounted on the secondary air inlet ducts to the lower 7 and upper burners 15. The control flaps 23 allow for adequate mixing between the secondary air and the recirculated gases as well as complete elimination / the closure of secondary air or recirculation gases in front of the burner. The recirculation gases and secondary air are mixed in the mixing chamber 24 just before entering the burner. The amount of recirculated gases flowing through the drive fan 22 is determined by the composition of the recirculated gases, the oxygen and carbon monoxide content and the technological requirements of the combustion chamber temperatures.

Vsi sestavni elementi recirkulacije: kanali, ventilator, lopute morajo biti dobro toplotno izolirani. Površinska temperatura elementov mora biti nižja od 40 °C.All recirculation components: ducts, fan, flaps must be well insulated. The surface temperature of the elements must be below 40 ° C.

Claims

PATENT APPLICATIONS

A ring shaft furnace for calcining lime by recirculating the gases from the furnace, characterized in that a duct is formed between the duct (2) of the exhaust gases from the recuperator (3) and the secondary air inlet ducts to the lower (7) and upper (15) burners. recirculation gases, by which the fan (22) pushes the recirculation gases through the control flaps (23) and the mixing chambers (24) into the lower (7) and upper (15) burners.

Apparatus according to claim 1, characterized in that the recirculation gases are withdrawn from the exhaust gas duct (21) at the place of their highest temperature, that is, immediately after the exhaust gases exit from the recuperator (3).

Device according to claim 1, characterized in that a fan (22) is used to drive the recirculation.

Apparatus according to claim 1, characterized in that the mixing chamber (24) for recirculating gases and secondary air is positioned immediately before entering the burner.

Apparatus according to claim 1, characterized in that all the components of the gas recirculation are thermally insulated so that the temperature on their surface does not exceed 40 ° C.