| 摘要 |
<p>A process and apparatus for measuring carbonate and sulfide concentrations in white and green pulping liquor and in the slaker/causticizing (S, C1) cells and controlling the causticizing reaction and other stages using this information. Specifically the causticizing control logic is based on determining the concentration of sodium carbonate and sodium sulfide (GC/A) in the green liquor, in the white liquor-mud slurry at the slaker or first causticizer (ML3) and in the white liquor being sent to the digester house and using this information to control the entire process. Th e concentration and flow rate of the green liquor may be measured and controlled quite easily. The proposed strategy will control the green liquor flow rate (V41) to the slaker to maintain the desired Na2CO3 concentration in the slaker/causticizer liquor despite variations which occur in the lime. The green liquor concentration is also controlled in a control loop. Weak wash liquor (L40) is added to the green liquor to maintain the concentration of the Na2CO3 in the green liquor. The slaking/causticizing process is controlled by adjusting the flow rate and concentration of the green liquor. This strategy will control the process based on direct measurements of the critical component in the system, sodium carbonate. The green liquor flow rate will be automatically adjusted by a control loop to maintain the desired Na2CO3 concentration in the white liquor. The last measurement is to determine the concentrations of sodium hydroxide, sodium carbonate, and sodium sulfide in the white liquor which is sent to the digester house to be used in the cooking process. It is important to measure the sodium hydroxide and sodium sulfide concentrations in the white liquor (RS3, GC/A) so that the amount of liquor to be charged in the digester(s) may be correctly determined. Changes in sodium sulfide concentration (generated at the recovery boiler) can affect white liquor (AA/EA) concentration. </p> |
