Spray dryer is a thermal process to make liquid material atomized into fine mist droplets through nozzle, contact with hot medium in drying tower, and be dried into powder. The feed can be solution, suspension or paste, atomization can be achieved by rotary atomizer, pressure atomizing nozzle and airflow atomizing nozzle, the operating conditions and the design of the drying equipment can be selected according to the required drying characteristics of the product and the specifications of the powder.
Spray dryer is the fastest growing drying field, the widest range of applications of a form, suitable for solutions, emulsions and pumpable suspensions and other liquid raw materials to generate powder, granular or block solid products. Being dried material thermal sensitivity, viscosity, fluidity and other different drying characteristics, and product particle size, particle size distribution, residual moisture content, bulk density, particle shape and other different quality requirements, determines the use of different atomizers, air movement and drying chamber structure form.
Ball milled slurry in the mixing tank is further stirred and heated to 35 ℃ or more, and then the pressure is applied to the mixing tank, under the action of pressure, the slurry is sent to the atomizer, through the atomizer after the atomization of the lower part of the tower from the tower body sprayed into the body. The N2 heated by the oil and gas heat exchanger is sent to the gas distributor at the top of the tower by the blower, and after the gas distributor, the N2 enters the tower uniformly and cyclone-like, and the atomized slurry is dried and granulated. After contacting with the hot gas, the liquid on the surface of the granule will evaporate rapidly, while the gas inside will migrate to the surface and be taken away by the hot gas in the subsequent drying process. The dried pellets fall to the bottom of the tower and are recovered through a pair of disk valves.
The gas after drying the slurry contains vaporized hexane and a small amount of fine dust, which is sent by the pressure fan to the cyclone separator for initial separation of the dust before being sent to the condensation and rinsing tower. In the drenching tower, the gas is fully scrubbed, and the hexane contained in the gas is condensed out and collected at the bottom of the drenching tower, and the scrubbed gas is sent to the oil and gas heat exchanger for heating and reuse. During the operation, the system maintains a slightly positive pressure state, which is automatically controlled by a gas delivery valve and an exhaust valve.
To avoid the shortcomings of hot air vortex and axial flow, set up a hot air rectification chamber, in the rectification chamber of the blowing outlet is equipped with a honeycomb similar to the rotary turbine impeller guided impeller of the fixed blade, the hot air by the fixed blade of the radius of the direction of the outflow, and further change the direction of the hot air, blowing to the drying tower. In this way, the fixed blade transforms the hot air of the vortex into the axial supply of the drying tower to achieve the purpose of rectification, which is very effective in solving the problem of product adhesion in the drying tower. And the rectification prevents the hot air from rotating, so that when the mist falls, it is heated uniformly, so that the thermal change of the finished product can be maintained at a minimum, thus improving the quality of the finished product.