Closed-loop Spray Dryer

Overview

  This system uses circulating nitrogen instead of air and organic solvents instead of water for spray drying. In addition to product recovery, it can also recover organic solvents. The design and construction fully take into account pressure resistance, sealing performance, explosion-proofing, pressure control, oxygen concentration control, etc.
  It is mainly aimed at the spray drying of organic solvents (such as formaldehyde, ethanol, acetone, chloroform, etc.). The drying medium is mainly nitrogen, with the system sealed and the drying medium circulated, and the solvent can be recovered through condensation and other methods. It is widely used in industries such as cemented carbide, lithium batteries, ceramics, and pharmaceuticals.

Working Principle

  Before starting the closed-loop spray dryer, an inert gas (such as nitrogen) is first introduced into the sealed drying tower to expel the air. The feed liquid is pumped to the atomizer (usually a centrifugal type) and atomized into fine droplets. Meanwhile, the inert gas is heated by a heater and enters the drying tower, where it undergoes sufficient heat exchange with the droplets, causing the liquid component (water or organic solvent) in the material to evaporate instantly. The dried powder product is discharged from the bottom of the tower. The hot and humid gas carrying vapor then enters the subsequent dust removal system (such as a cyclone separator and bag filter), and then enters a condenser, where the vaporized organic solvent is condensed into liquid and recovered. The non-condensable inert gas, after solvent removal, is reheated and re-enters the drying tower as the drying medium for circulation. The entire system generally operates under positive pressure, and the make-up gas volume is automatically controlled by a pressure transmitter to maintain pressure balance.

Features

  Due to the inert gas environment and fully enclosed operation, the system effectively prevents product oxidation and ensures the quality of heat-sensitive or easily oxidized materials. Its solvent recovery function is a core advantage: the condensation system can recover organic solvents from the feed liquid, with a recovery rate typically reaching over 85%, or even exceeding 99%, reducing both costs and pollution. The fully enclosed design results in an extremely high product yield, with almost no powder leakage, achieving yields of 95% to 100%. In addition, the system offers high safety, eliminating the risk of combustion and explosion. It is also environmentally friendly, enabling low-pollution or even zero-pollution operation, and eliminating the need for odor treatment equipment. Furthermore, it enables low-temperature drying (below 100°C), making it particularly suitable for processing heat-sensitive materials.

Applications

  1、Non-oxide ceramics, cemented carbide, battery materials.
  2、 Seasonings, health products.
  3、 Pharmaceuticals, vitamins, organic drugs.

Flow Diagram