Closed cycle flash dryer for Captan

Captan, also known as Capeton, is a broad-spectrum, low-toxic fungicide. It belongs to the traditional multi-site organic sulfur fungicide and is widely used in agricultural production. It is mainly protective and has certain therapeutic effects.
The process of drying captan is relatively mature. Most of them use airflow rotary flash drying equipment, and the efficiency and output can meet the production of large-scale enterprises. However, there is a disadvantage of using airflow drying equipment, which is that a large amount of tail gas is generated, which is bound to cause great environmental pressure. Under the general situation that the country advocates environmentally friendly production and pays close attention to environmental protection, the heat of the tail gas can be utilized and cooled and dehumidified, which can fundamentally solve the fatal weakness of airflow drying equipment.

Brief description of the principle:
The flash dryer generally needs to meet the following two conditions: one is the humidity difference of the process gas, and the other is the temperature difference. The important of these two conditions is the humidity difference (the temperature difference only determines the energy consumption efficiency of drying, while the humidity difference determines whether the dried finished product can reach the final moisture). Therefore, the closed-loop drying equipment for tail gas focuses on cooling and dehumidifying the tail gas and cooling and dehumidifying the tail gas requires energy consumption (in principle, about 50-70% of the heat required for drying is in the tail gas of the time). The tail gas is passed through the tail gas heat exchanger (waste heat recovery and heat exchange between the tail gas and the process air after cooling and removal). On the one hand, the humidity of the tail gas after heat exchange is close to but slightly greater than the dew point temperature of the tail gas (calculated to be about 40°C), and on the other hand, the process air is preheated to reduce the amount of steam used (energy saving is more obvious in winter). In this way, energy saving is achieved (the process air is heated and the amount of refrigerant is reduced, but at this time the tail gas does not condense, so it can be cleaned regularly and more easily). Secondly, the wet air enters the condenser and is discharged with the condensed water. The wind after passing through the condenser continues to circulate to the heater for secondary heating, thereby ensuring that the gas is not discharged or discharged less, thereby achieving the purpose of environmental protection and energy saving.