AGITATION SCALE-UP MODEL FOR THE SUSPENSION POLYMERIZATION OF VINYL-CHLORIDE

Studies were carried out to develop a mathematical model based on expe rimental results to correlate agitation and other polymerization param eters with the particle size of PVC and to specify the limits of agita tion speed within the defined agitation system. Computer regression an alysis of about 30 vinyl chloride polymerizations in reactors with 10 L to 27 m(3) tank volume are carrried out. The particle size of PVC (d (50)) is correlated to various polymerization parameters such as impel ler diameter (D), impeller speed (N), reactor tank diameter (T), liqui d height (H,) and tank volume (V) (N-We = Weber number): d(50) = 4346. 8 (N)(-0.905) (D)(-0.901) (T)(0.514) (H-l)(-0.131) d(50)/D = 273292.1 N-We(-0.51) N-min = 3049.1 D--1.1 (T/D)(-0.113) In these equations onl y the values 3 049.1, -0.113, 4346.8 and 273 292.1 depend on the recip e. When the recipe is changed these variables must be determined by on e or two bench-scale polymerizations to adjust the correlations to the new recipe conditions so that they can be also used for scale-up purp oses with the new recipe.