Coal mining brings a large amount of coal slime resources. Therefore, it is necessary to take measures to change the operating conditions of drying equipment, choose drying equipment with high thermal efficiency, and recover part of the heat in the exhaust gas to reduce production costs.

  1. Reduce various heat losses during the drying process

  Generally speaking, the heat loss of the dryer will not exceed 10%, and the heat loss of the large and medium-sized production equipment is about 5% if the heat preservation is appropriate. Therefore, do a good job in the insulation of the drying system, but it is not that the thicker the insulation layer, the better, a good insulation layer thickness should be determined.

  In order to prevent the 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 adjustments, which can prevent the convection dryer from drying due to the leakage of the drying medium or the leakage of ambient air. The thermal efficiency of the machine has decreased.

  2. Reduce the evaporation load of the dryer

  Before the material enters the dryer, it can increase the solid content in the material and reduce the evaporation load of the dryer through filtering, centrifugal separation or evaporation of the evaporator. This is one of the effective ways to save energy for the drying equipment.

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

  3. Increase the air temperature at the inlet of the dryer and reduce the temperature of the exhaust gas at the outlet of the dryer

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

  4. Partial exhaust gas circulation

  As part of the waste heat in the exhaust gas is used to improve the thermal efficiency of the dryer, as the amount of exhaust gas circulation increases, the moisture content in the hot air increases, and the drying rate will decrease accordingly, making the drying time of the wet material The increase brings about an increase in the cost of drying equipment. The general exhaust gas circulation volume is 20%-30%.

  5. Recover heat from the exhaust gas from the dryer outlet

  In addition to the above-mentioned energy-saving method of using part of the exhaust gas circulation to recover heat, indirect heat exchange equipment can also be used to recover heat from the exhaust gas at the outlet of the drying equipment and other energy-saving ways. Commonly used heat exchange equipment include heat wheel heat exchangers, plate heat exchangers, heat pipes, heat pumps, etc.

  If you want to know more about slime dryer, please feel free to contact us.