sugar bleaching with ozone preliminary tests

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  • SUGAR BLEACHING IN AGROctober 2000

    PRELIMINARY EVALUATIONby

    H. Pareja, A.C. Moutella, R. Yoshida

  • OVERVIEW Ozone to bleach sugar proved to be

    technically feasible in agitated reactor. However, consumption were high. No toxicity was detected at all, but At long contact time or high Ozone dosage,

    off-flavors were noticed. To remove these off-flavors, additional step

    applying CaCO3 was proposed.

  • Objectives Establish best conditions to AGR operation. Evaluate AGR performance to bleach sugar

    with Ozone. Acquire kinetics information. Acquire parameters to scale-up Adjust O3 generator.

  • Test programbatch motor

    inj. Sup inj meio suco afogado tempo 3000 2000 1000 500 6% 10% rotao1 x x 60 x x 5002 x x 60 x x 5003 x x 60 x x 5004 x x 60 x x 5005 60 x x 5006 60 x x 5007 60 x x 5008 60 x x 5009 60 x x 50010 60 x x 50011 60 x x 50012 6013 60 30014 60 50015 60 50016 60 menor17 60 livre livre livre livre livre livre livre18 60 livre livre livre livre livre livre livre

    observ.teste

    avaliar efeito conc. O3

    nvel reatorponto de injeo dosagem de O3 conc. O3

    livre

    sem O3

    para definir melhor condio operacional

    otimizando cintica de ozonizao

    est. consumo energia p/ agitaraval. red. de potncia melhor condio

    repetir melhor condio

    para testes confirmatrios

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  • UPDATE Tests

    AGR pilot scale 200 liter nominal Ozone generator capacity: 1.5 Kg/h Ozone concentration: 5-7% 5 tests, 25 samples, 100 analysis

    Product parameters color, Brix, pH and turbidity

  • Lets see the work Next, a graph represents the results obtained. It is important to notice that initial color shows a good

    value of below 200 icumsa. Average values can be considered 400 and worst 800

    icumsa These tests evaluated the best position inject ozone, if at

    the entrance of the vortex or at the end of the draft-tube. It was also evaluated if the reactor would be work with

    (favor headspace suction) or without vortex (favor internal recirculation).

  • Main Results

    0

    50

    100

    150

    200

    250

    0 20 40 60 80TIME (min.)

    color

    (icum

    sa)T1T3aT4aT3bT4b

  • Confused? Although logical, the results are dificult to

    evaluate. Color decreases quickly, but as it lowers the

    value , the decoloring reactions reduces its kinetics.

    It seems that this reactions has a logartimic behavior , like C = Co ekt.

    So, lets see as a log graph.

  • Log evaluationy = -0,0121x + 2,1548y = -0,014x + 2,2801

    y = -0,0162x + 1,9687

    y = -0,0123x + 2,1154

    y = -0,016x + 1,9798

    0,0

    0,5

    1,0

    1,5

    2,0

    2,5

    0 20 40 60 80time (min.)

    log Co

    lor

    T1 T3T4 T3T4 Linear (T1)Linear (T3) Linear (T3)Linear (T4) Linear (T4)

    Best results

    Despite lines seem to equal. O3 dosage for T4 was higher

    T1 - Inj. Super., vortexT3 - Inj. Infer, vortexT4 - Inj. Infer, no vortex

  • Too much math and info? Humm! Ok. Just take attention to these

    observations: Log graphs are better to analyse this process. A straight line represents the process using an

    AGR. But more data have to be collected. More inclined is the line, more quickly the

    color decreases . Next we are going to see the effect of the

    dosage

  • 0

    50

    100

    150

    200

    250

    0 500 1000 1500 2000 2500dosage (mgO3/L)

    color

    T1T3aT4aT3bT4b

    Dosage and Color

    Very low values were achieved

  • Comparing to previous tests

    0,0

    0,5

    1,0

    1,5

    2,0

    2,5

    3,0

    0 2000 4000 6000dosage (mgO3/L)

    log (C

    or)log AGRlog conv.Linear (log AGR)Linear (log conv.)

    AGR values lower than conventional

  • Preliminary Conclusions AGR is better than conventional reactors for

    sugar bleaching with ozone. During the tests initial color was very low. AGR reduces ozone consumption by 30%

    under current test condition. AGR works stable. Ozone generator did not

    showed stability.(?)

  • Next work New tests have to be programmed with

    higher initial color. Effect of higher ozone concentration has to

    be evaluated. Kinetics will be evaluated. Process conditions will be defined.