The present invention relates to method and apparatus for preheating pulverous materials, such as glass batch constituents, prior to their introduction into a melting furnace to increase the efficiency and output of the melting installation. The pulverous materials are passed downwardly through a shell and tube preheater with sub-atmospheric pressure over the pulverous material to remove the contained moisture in vapor form from an upper region of the preheater. The decreased atmospheric pressure prevents moisture condensation and build-up on the pulverous material within the tubes, especially in cooler areas, which can cause tube pluggage. The subject invention is of particular utility to the glass industry, and especially glass melting furnaces, but is also applicable to other types of shell and tube heat-exchange applications.