Discharging Batch

When the batch is complete, the material must be discharged as soon as practical into the dispatch container. The viscosity at this point will be low to assist in flow. 

The drums must be clean and dry before being filled. The inside of the drums must be coated with either a phenolic or epoxy resin to provide resistance against attack from the prepolymer. The wall thickness must be sufficient to prevent collapse due to a vacuum being formed as the material cools and contracts. Prior to sealing the drum, nitrogen should be introduced into the free space in the drum. 

IBCs (intermediate bulk containers) must be clean and dry and made from material that can resist the temperatures when filling the container. The discharge temperature may have to be lowered to cope with the initial temperature of the prepolymer. 

If a recirculation pump is fitted to the reactor, the material may be discharged from the pump circuit. The valving must be such that the material is recirculated when not being discharged. Pressure relief valves also must be fitted to the pump. 

The prepolymer also may be discharged by gravity into the container. Nitrogen gas pressure may be used to assist the flow of prepolymer. 

---

Screw-Discharge Batch Mixers A variant of the sigma-blade mixer is now available with an extrusion-discharge screw located in the saddle section. During the mixing cycle the screw moves the material within the reach of the mixing olades, thereby accelerating the... 

Screw-Discharge Batch Mixers A variant of the sigma-blade mixer has an extrusion-discharge screw located at the center of the... 

Vertical basket with bottom plough discharge batch, particle diameter 5-500 pm feed solids concentration 9-90% w/w capacity 0.1-1.25 kg/s. Product dryness 25-60% solids. Use with free draining, medium capacity, and where need multiple rinse. 

Vertical basket, bottom discharge batch with cycles accelerate to load speed, load and cake formation, accelerate to wash, wash, accelerate to full speed, spin dry, decelerate to unload speed, unload 3-120 s. Cycle time for free draining 2-6 min slower draining materials cycle time 20-30 min with some > 60 min. area per unit 0.4-4.5 m cake volume 0.018-0.53 m about 67 % of feed volume cake thickness 50-150 mm with smaller thickness in smaller diameter centrifuges. 900-1800 rpm. Basket diameter 1-1.2 m L/D = 0.5. 

Horizontal basket, plough discharge batch with cycles load 7-25 s wash 5-25 s, spin dry 12-30 s, unload cake 3-12 s total cycle time 20 s-15 min but usually... 

---