7884079643

moment to introduce the relation C_uf = 100 - A_fa as the unburned carbon in the fły ash. For this reason, Eq. (4) can be rewritten as

ah£a^p i C_u Q\ U00 -

In this equation, a_fa has been considered equal to 1 (Eq. (8)) taking into account the experimental results and calcu-lations, with a high confidence level.

It can be observed that the above simplifications to calculate for q₄ and q₅, reduce and simplify the number of statistical models to be fitted to obtain the claimed efficiency chart. In the next paragraph, the statistical models fitted to calculate C_uf, CO/(CO + C0₂) and stack temperaturę, T_eg, will be discussed. It should be noted that the last parameter, T_tg, is needed to calculate the exhaust gases enthalpy in Eq. (2).

In order to obtain a simplified model, the influence of the stoichiometric ratio in the furnace («f) and steam power (D_sh) on the unburned carbon in the fly ash, C_Uf, has been plotted. Results of the experimental measurements are depicted in Fig. 2. As can be seen, the unburned carbon increases with increasing steam power and decreases with increasing stoichiometric ratio in the furnace. As steam power is raised at a constant stoichiometric ratio, both the amount of bagasse fed and the combustion air flow ratę increase, sińce the air volumetric flow ratę per unit weight of bagasse is fixed. This, in tum, increases the average gas velocity in the fumace and the fraction of fuel that burns in suspension, rather than in the bed on the stationary grate. The shorter residence time available for combustion in suspension results in an increased unburned carbon carry-over and poorer combustion performance. Therefore, when steam power and bagasse consumption are increased, a higher stoichiometric ratio in the fumace is needed to achieve the same carbon conversion (C_Uf). Taking into account all the experimental data, a statistical model is fitted

C_uf (kgę/kgfa) = 0.854965 + 0.002724D_sh reproducing the experimental dependence of C_Uf on both the stoichiometric ratio at the furnace, a_f, and the steam power, D_sh. In this equation D_sh has units of t/h.

Once <74 is calculated, q₃ and q₂ can also be evaluated. To determine the Chemical carbon heat loss (q₃), the parameter Rcon needs to be calculated by the equation

C^p + 0.375S^P 100

/iico/c being the CO-to-C molecular weight ratio. C^p and S^p are the carbon and sulfur contents of bagasse from ultimate analysis (as received). CO and C0₂ are the carbon monoxide and dioxide concentration in the stack gases, respectiveiy. Substituting Rcon >ⁿ Eq. (3), only the term containing CO and C0₂ remains to be determined from the experiments in order to establish a correlation for the Chemical carbon loss, q₃. Results are presented in Fig. 3, showing a linearly decreasing dependence of this term for increasing stoichiometric ratio, and a weak influence of the steam power. For clarity, in this plot, error bars are only displayed for the measurements corresponding to steam powers of 20 and 50 t/h, respectively. The remaining experimental points represent the mean values for

Wyszukiwarka

Podobne podstrony:
That is in formal words, but for your information the effect is to introduce the Office of past pres
message 16 Are you surę you want to ouit the Fishing Trio?
16 (100) Swćzność środków odkażających zależy od : entpctalury wilgotności )H :zjsu ekspozycji wszys
Zawody i płace w ubezpieczeniach Mediana Kwartyl trzeci Aktuariusz 7 800 zł 13 900 zł 16 100
7 String Electric Guitars - Tubę Amps - Combo from $200 to $2000    $100 to $100
58846 P1010016 (16) 100 Richard Sheppard Równie forsownie przyciągając uwagę czytelnika tak do wzglę
16 (100) sCeznoŚć środków odkażających zależy od
img100 (16) 100 100 Bys, 112 2,3.2.4. Sprawdzęnip i rektyfikacja teodolitu ?/ każdym teodolicie mogą
DSC16 (2) Muller obszernie i z rozgłosem światowym w czterech dziełach: Introduction to the Science
16-100 Sokółka ul. Mariańska 31 tel.: 85 711 25 71    * SOKÓŁKA
DSC02362 (2) S02 + CaC03—>CaS03 + C02 S031 CaC03-+CaS04 + C02 1 mol CaC03 wiąże i mol S02 M <C

więcej podobnych podstron