Dropwise adding apparatus and dropwise adding method for cold light process of 3,5-dichlorophenyl isocyanate

The invention provides a dropwise adding apparatus and a dropwise adding method for a cold light process of 3,5-dichlorophenyl isocyanate. The dropwise adding apparatus includes a dropwise adding kettle, a cold light kettle, and a material pipeline and a condenser therebetween. To ensure that the dropwise adding process is carried out successfully, a first pressure sensor and a second pressure sensor as well as a nitrogen gas auto-valve which is linked thereto are disposed. The dropwise adding kettle and the cold light kettle are connected to the same one tail gas system, so that external pressure condition during the dropwise adding process is constant. To ensure that the dropwise adding process of the next batch is carried out successfully, a solvent inlet is added to the lower part of the dropwise adding kettle and is used for flushing the material pipeline after the material is dropwisely added in this batch and preventing wall adhesion of the material and blocking during the dropwise adding process. For