Rectifying and spray-freezing drying method for preparing polyethylene oligomer powder

Abstract

The invention relates to a rectifying and spray-freezing drying method for preparing polyethylene oligomer powder. The method comprises the following steps: (1) performing indirect heat exchange between a polyethylene wax solution and saturated steam, thereby separating a solvent, methylbenzene, from polyethylene wax; (2) performing indirect heat exchange between the solvent, methylbenzene, and a cooling medium for cooling the solvent, methylbenzene, till the solvent, methylbenzene, is in a liquid state, and circulating part of methylbenzene in a liquid state in a rectifying tower while discharging the rest; and (3) dividing the polyethylene wax solution into two parts, heating one part with saturated steam and returning the heated part into the rectifying tower to obtain steam condensate and discharging the steam condensate, and conveying the other part into a spray-freezing tower to form vaporific polyethylene wax drops, performing heat exchange between the drops and cold nitrogen to obtain powder and nitrogen containing superfine powder, purifying the nitrogen containing superfine powder to obtain superfine powder and purified nitrogen, and performing supercharging and cooling on most of the purified nitrogen and then returning the nitrogen into the spray-freezing tower while feeding the rest into an exhaust treatment system. The rectifying and spray-freezing drying method has a simple operation process and is high in heat efficiency.

Description

Technical field [0001] The invention relates to the technical field of freeze spray drying of flammable and explosive materials, in particular to a "rectification + freeze spray" drying method for preparing polyethylene oligomer powder. Background technique [0002] At present, the conventional drying technology of polyethylene wax powder is to spray the solution of polyethylene wax through a nozzle under pressure to spray mist-like droplets in the drying tower, and then co-currently descend with hot nitrogen. Most of the powder particles are discharged from the tower. The bottom discharge port is collected, and the evaporated waste gas and the small powder contained in it are separated by the cyclone separator and discharged by the suction fan, and the powder is collected from the lower end of the cyclone separator. This method has a short drying time, but when the air temperature is lower than 150°C, due to the low volume heat transfer coefficient, a larger equipment volume is ...

AI Technical Summary

Problems solved by technology

This method has a short drying time, but when the air temperature is lower than 150 °C, due to the low volume heat transfer coefficient, a larger equipment volume is required; in addition, due to the encapsulation of the particles, the amount of solvent carried in the product is more; for The separation requirements of gas-solid mixture are relatively high, generally two-stage dust removal is required, the operation process is complicated, and the thermal efficiency is not high

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