Drying method and apparatus of the sludge

PROBLEM TO BE SOLVED: To dry sludge in a short time and decrease production of odors and carbon dioxide by alternately performing the step of evaporation effected by evacuating an interior of a container while the container is continuously heated and the step of heat transfer effected by introducing air into the container. SOLUTION: A sludge conveyance tube 5 is connected in communication with a right side end face of a vacuum container 2 having a horizontally- disposed circular cylindrical shape for containing sludge 1 and a stem introduction tube 10a is connected in communication with a left side face so as to introduce steam through the steam introduction tube 10a and discharge air within the vacuum container 2 through an air discharge tube 10b and the air within the container 2 is replaced by the steam. Steam is continuously supplied to a jacket of the vacuum container 2 for heating, and the sludge 1 in a sludge hopper 7 is supplied from one side of the container 2 by a sludge pump 8 and simultaneously the steam in the vacuum container 2 is sucked by a vacuum pump 27. At this time, air invades an interior of the vacuum container and penetrates into clearances of powdery particles of the sludge so that heat is transferred through convection.