| 摘要 |
PURPOSE: A modular reactor system allowing control of particle size during chemical precipitation is provided to obtain a relatively monodisperse distribution of precipitated particles. CONSTITUTION: The modular reactor system is of a vertical design wherein the product flow is against gravity. A rotating shaft(a) anchored by means of a steady bearing(g) provides power to drive an impeller(e1). One or more reactants(optionally heated) enter the mixing zone(R1) through one or a plurality of ports; two are shown as (f1) and (f2). Ports are separated by the greatest possible distance as measured along the circumference of the mixing zone. A single baffle(q) or a plurality of baffles is included within R1 to improve turbulent mixing. An end cap(h) ensures that the product flow is upward. Backmixing is minimized by the inclusion of a back-mixing preventor(c1), which consists of a thin perforated diaphragm of diameter greater than that of the reactor tube. The size of the perforation(s) is such that product may move freely through them but they are not so large as to allow significant backflow of product into the reactor section. The size and number of the perforations that are required are determined by the flow rate of the reactants, the turbulence within the mixing zone and the viscosity of the medium. The back-mixing preventer is sealed by two "O" rings(d1 and d2) which are held in place by means of two bolted flanges(b1 and b2). The product exits the reaction zone into a quiescent zone j1; the reaction is continued in this zone by means of diffusion of the reactants if it has not previously gone to completion in the mixing zone R1. Optionally, j1 may be heated by means of a jacket or internal coil. In the simplest set-up, the product is exited j1 by means of an overflow pipe.
|
