Abstract: A dryer system, such as is used in a pulverizing mill assembly, includes a hot gas generator which supplies drying gas to the starting point for a gas circulation system. The drying gas passes through the circulation system commingling with particles to be dried. The dried particles are removed whereupon the system gas flow is divided into a return portion and a spent portion for expulsion to ambient. Part of the system return flow is further freed of particles, compressed, and supplied to the hot gas generator as secondary gas. The return gas flow into the generator is regulated to control hot gas temperature in response to generator flow temperature. In addition, hot gas temperature may be controlled in response to system gas temperature by regulation of fresh primary air flow to the generator. Exhaust gases from the hot gas generator are introduced into the system return flow at the circulation starting point to repeat the process.

Abstract: Method and apparatus for operating a process in which combustible solid particles are mixed during processing with air and circulated through a plurality of stages, thereby tending to build up an oxygen enriched combustible mixture during shutdown, the invention involving adding additional fuel to the oxygen enriched combustible mixture during such shutdown in a closed burner system, burning the resulting mixture in the closed burner system, and recirculating the flue gas from such combustion back into the plurality of stages to thereby function as an inert gas to prevent accidental combustion or explosion.

Abstract: An apparatus and method for the safe preparation of pulverized coal comprises the steps of mixing coal with an inert gas in a pulverizing mill, separating dry coal dust from an exhaust gas bearing a residue of coal dust in a separator, mixing the exhaust gas with additional inert gas and filtering the coal dust from the gas mixture in a filter.

Abstract: A drying-grinding apparatus including two types of grinding means, one being arranged to produce a relatively coarse ground product, and the other being arranged to produce a relatively finely ground product. A drying gas is introduced into each of the grinding means, and a common conduit delivers the ground products from both of the two grinding means into a sifting means. The sifting means discharges relatively coarse particles into a metering means which receives the output from the sifting means and separates the same into two fractions one of which is returned to the coarse grinding means, and the other of which goes to the fine grinding means.