biomass microwave pyrolysis system
Author: langfeng Time: 2019-01-09
An important process parameter is the residence time. The fast internal heating causes fast release of moisture from the feedstock and, in consequence, a growth in the volatile substances release area during the pyrolysis process. In a microwave reactor, volatile vapours (including small dipolar molecules) loaded with solid particles (chiefly fine particles of the carbonization product) can be easily heated by microwaves to a higher temperature. Therefore, the pyrolytic vapours must be carried away from the reactor very quickly for the secondary cracking of the vapours within the reactor space to be reduced and for water vapour to be removed. The efficient microwave energy transfer to the feedstock in the bed is another important issue related to the microwave reactor. The reactor vessel, made of materials transparent to microwaves (e.g. quartz), must be carefully and appropriately cleaned, especially at continuous operation mode. The presence of solid particles in the vapours and fine carbon particles on the vessel walls will cause significant difficulties in introducing microwaves into the reaction environment or even local burns of the reaction vessel. It is also important that the feedstock mixture should be homogenous for the microwave field action in the reactor to be uniform and for the forming of ignition points (“hotspots”) to be thus avoided. The hotspots may easily cause the loss of control of local pyrolysis temperature and, thus, of the entire reaction process.