Energy saving method for spray drying equipment

The spray drying equipment is a new type of high-efficiency drying technology equipment, which can spray the materials of solution, emulsion, suspension and paste into dry powder, fine and medium granular products. It is fast, efficient, and has fewer processes and labor savings.

Energy saving method for spray drying equipment

(1) Reducing the heat loss of the drying process Generally speaking, the heat loss of the dryer will not exceed 11%, and the heat loss of the large and medium-sized production equipment is about 6% if it is properly insulated. Therefore, it is necessary to do the insulation work of the dryer system, but it is not the thicker the insulation layer, the thickness of the insulation layer should be determined.

In order to prevent leakage of the drying system, the blower and the induced draft fan are generally used in series, and the system is operated in a zero-pressure state after reasonable adjustment, so as to avoid drying of the convection dryer due to leakage of the drying medium or leakage of ambient air. The thermal efficiency of the machine has decreased.

(2) Reducing the evaporation load of the dryer Before entering the dryer, the pre-dewatering treatment such as filtration, centrifugal separation or evaporation of the evaporator can increase the solid content in the material and reduce the evaporation load of the dryer. One of the effective ways to save energy in dry equipment.

For liquid materials (such as solutions, suspensions, emulsions, etc.), pre-treatment before drying can also save energy, because heating materials in the convection dryer uses air sensible heat, while preheating uses water. Latent heat or waste heat of steam. For spray drying, preheating of the feed liquid also facilitates atomization.

(3) Increasing the air temperature at the inlet of the dryer and reducing the temperature of the exhaust gas at the outlet of the dryer

As the definition of the thermal efficiency of the dryer, it is known that increasing the inlet air temperature t1 of the dryer is advantageous for improving the thermal efficiency of the dryer. However, the inlet air temperature is limited by the product's allowable temperature. In a co-current particle suspension dryer, the surface temperature of the particles is relatively low, so the inlet air temperature of the drying equipment can be much higher than the allowable temperature of the product.

(4) Part of the exhaust gas cycle

The drying system using part of the exhaust gas circulation is shown in the figure. The heat efficiency of the dryer is increased by utilizing part of the residual heat in the exhaust gas, but the moisture content in the hot air is increased as the exhaust gas circulation increases, drying The rate will be reduced, which will increase the drying time of the wet material and increase the cost of the drying equipment. Therefore, there is an exhaust gas circulation amount. The general exhaust gas circulation is 20% - 30%

(5) Recovering heat from the exhaust gas of the dryer outlet

In addition to the above-mentioned energy-saving method for recovering heat by using part of the exhaust gas cycle, it is also possible to adopt an indirect heat exchange device to recover heat from the exhaust gas of the drying device, and the like, and the commonly used heat exchange device has a heat wheel heat exchanger, Plate heat exchangers, heat pipes, heat pumps, etc.