Matematičko modeliranje nastanka dušičnih oksida u ložištu generatora pare

Madžarević, Pavo (1999) Matematičko modeliranje nastanka dušičnih oksida u ložištu generatora pare. = Scientific master's thesis , Sveučilište u Zagrebu, Fakultet strojarstva i brodogradnje, UNSPECIFIED. Mentor: Bogdan, Željko.

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Abstract (Croatian)

U prvom, uvodnom dijelu, postavljen je problem i cilj, te iznesena ocjena dosadašnjih rezultata istraživanja emisije dušičnih oksida. Navedene su metode i opisana struktura i sadržaj rada vezanog za matematičko modeliranja procesa izgaranja i nastajanja dušičnih oksida (NOX) u ložištu industrijskog generatora pare [1-81]. U drugom dijelu obrađene su teorijske osnove dušičnih oksida. Obuhvaćene su sve vrste dušičnih oksida (NO,,), njihova kemijska i fizikalna svojstva, oblici, porijeklo, uvjeti i mehanizmi tvorbe i razlaganja značajni za proces izgaranja. Spomenut je njihov udio u ložištu i plinovima izgaranja, zatim njihove sumarne kemijske reakcije i oslobođene topline, te utjecaj na zagađivanje atmosferskog zraka i okoliša. Obrađeni su principi i tehnike smanjivanja emisije dušičnih oksida u složenim homogenim i heterogenim reakcijama kinetičkog i/ili difuznog procesa pretvorbe tvari i topline. Opisane su primarne i sekundarne mjere, kao i različiti postupci i izvedeni uređaji za smanjivanje dušičnih oksida. Pritom su korišteni objavljeni rezultati teorijskih i eksperimentalnih istraživanja dobivenih na pilot postrojenjima i u pogonskim uvjetima [1-37]. U trećem su dijelu razrađene opće osnove modeliranja izgaranja u ložištima i prikazan teorijski model izgaranja. Naznačena je svrha, primjena, uvjeti i klasifikacija problema izgaranja. Naglašene su bitne sastavnice i glavni postupci razvoja teorijskog modela izgaranja. Ispisane su jednadžbe za održanje mase i energije i transportne jednad2be u okviru k-s modela turbulencije. Opisane su jednad2be za udio smjese f (skalare) računate pomoću funkcije gustoće vjerojatnosti (FGV). \Nabrojane su opće pretpostavke korištene u modelima izgaranja. Za dobivanje prosječnih rezultata na kraju ložišta parnog kotla poslužio je model izgaranja prema normativnoj metodi CKTI. Pritom je određena koncentracija [\NO]=273 [ppm] na temelju adijabatske i stvarne temperature dobivene ovom metodom. Opći trodimenzionalni model izgaranja u ložištu s modelom emisije dušičnih oksida prikazan je kao neadijabatski toplinski i transportni proces. Taj model iz Fluent programa je primjenjen na parni kotao 50/64 [t/h] s uljnim lo2enjem. Osnova ovog rada su dobiveni i publicirani američki, engleski, japanski, njemački, ruski i domaći rezultati istraživanja [4-79]. U nastavku su prikazani rezultati mjerenja emisije dušičnih oksida na gore spomenutom parnom kotlu i opisan elektronski analizator rbr-ecom SGPLUS Analizirani su i uspoređeni rezultati dobiveni simulacijom i mjerenjem. Mjerenje i simulacija pomoću Fluent programa pokazuju vrijednosti termičkih, promptnih i gorivnih dušičnih oksida (NO,,). Dobra usklađenost rezultata opravdava ulo2ene napore modeliranja, simulacije i mjerenja, jer su potvrđeni u stvarnim uvjetima. Rezultati mjerenja i simulacije uspoređeni su s normiranim dopustivim emisijama dušičnih oksida za takva postrojenja u zemljama EZ. Te norme se primjenjuju i u nas. Usporedba pokazuje sasvim prihvatljive rezultate, bez obzira sto nisu poduzimane niti primarne, a niti sekundarne mjere. Tome doprinosi centrifugalni plamenik Saacke SKV 300. On lo2ivo ulje raspršuje u sitne kapljice (od 70 do 100 pm), te dobro raspodjeljuje i miješa sa zrakom. Uz kratko vrijeme zadržavanja i niske temperature, smanjuju se dušični oksidi. Prema mjerenjima koncentracija dušičnih oksida (NO) iznosila•je 289 [ppm] na kraju lo2ista [12-33,35,79,81].

Abstract

The first, introductory, part, sets out the problematic and the aim and expresses the evaluation of the results in the nitric-oxide emission research achieved so far. Adduced are the methods and the structure and content of the paper described regarding the mathematic modelling of the combustion process and modelling of the nitric-oxides (NO,,) production in the industrial steam-generator furnace [1-81]. The second part discusses the theoretical bases of nitric-oxides. Encompassed are all the nitric-oxide (NO,,) types, their chemical and physical characteristics, forms, origin, conditions and formation and decomposition mechanisms important for the combustion process. Cited are their participation in the furnace and the combustion gases, their summary chemical reactions and heat emission as well as their influence upon the pollution of the atmospheric air and the environment. The paper treats the principles and techniques of reduction with regard to the nitric-oxide emission in the complex homogeneous and heterogeneous reactions of a kinetic and/or diffusion process of the matter and heat transformation. Explicated are the primary and secondary measures as well as various procedures and the installed nitric-oxide reduction facility. Thereby, the published results of theoretical and experimental research obtained in the pilot plants and industrial-plant conditions were utilized [1-37,52-79]. The third part analyzes the general bases of modelling concerning the furnace combustion, and a theoretical combustion model is presented. Quoted are the purpose, application, conditions and classification of the combustion problematic. Emphasized are the essential components and the main procedures of development of the theoretical combustion model. Written are the mass-and¬energy conservation equations as well as the transport ones within the k-c turbulence model. Desribed are the equations pertaining to the mixture fraction f (scalars) calculated via probability density function (PDF). Enumerated are the general presuppositions utilized in the combustion models. In order to obtain the average results at the steam-boiler exit furnace, the combustion model in accordance with the normative CKTI method was used. Hereby, the [NO]=273 [ppm] concentration was determined based upon the adiabatic and real temperature created by this method. A general threedimensional of combustion model in the furnace with the nitric-oxide emission model is presented as a non-adiabatic thermal and transport process. This Fluent Program model was applied to the 50/64 [t/h] oil-powered steam-boiler. The basis of this paper are obtained and the published American, English, Japanese, German, Russian and domestic research results [4,6,8-79]. In addition, the measurement results pertaining to the nitric-oxide emission in the aforesaid steam boiler were presented and the electronic analyzer rbr-ecom SGPLUS were described. The results obtained by measurement and simulation are analyzed and compared. The measurement and simulation obatained by the application of the Fluent Program show the values of the thermal, prompt and fuel nitric oxides (NO,,). A good congruity of results justifies the efforts invested in modelling, simulation, and measurement since they have been confirmed in the real conditions. The measurement and simulation results have been compared with the normative allowed nitric-oxide emission for such facilities in the EC countries. These norms are being applied in Croatia as well. The comparison demonstrates quite acceptable results irrespective of the fail to implement both the primary and secondary measures. A contribution thereto is provided by the centrifugal Saacke SKV 300 burner. It disperses the heating oil in the tiny drops (70 to 100 µm), distributes them well, and mixes it with the air. With a short residence time and low tempertures, the nitric-oxide content is being decreased. According to the measurements, the nitric-oxide (NO) concentration amounted up to 289 [ppm] gat the exit furnace [12-33,35,79,81].

Item Type: Thesis (Scientific master's thesis)
Uncontrolled Keywords: matematičko modeliranje izgaranja u ložištu; matematički model dušičnih oksida; rotacijski (centrifugalni) plamenik
Divisions: 500 Department of Energy, Power Engineering and Environment > 510 Power Engineering and Energy Management Chair
Date Deposited: 22 Sep 2014 18:00
Last Modified: 16 Oct 2015 13:20
URI: http://repozitorij.fsb.hr/id/eprint/52

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