Three stage single pass high density drying apparatus for particulate materials

A rotary drum dryer, comprising:

• an elongated, hollow drum having a moist product inlet and a spaced dried product outlet, with a drying chamber between the inlet and the outlet;
• fighting within said drum dividing the chamber into a plurality of drying stages along the length of the chamber, including a first stage adjacent said inlet, a final stage adjacent said outlet, and at least one intermediate stage between the first and the final stages,
• said intermediate stage including a plurality of drying zones arranged in successive order from a point proximal to said first stage and extending towards the final stage, each of said zones configured to define a heat transfer ratio calculated by dividing the total heat-transferring surface area within the zone by the volume of the zone,
• one of said zones proximal to said first stage having a heat transfer ratio of from about 1.5-2.5 ft−1,
• another of said zones closer to said final stage than said one zone having a heat transfer ratio from about 2.75-3.75 ft−1,
• each of said zones including heat transfer fighting comprising a plurality of strut elements coupled to said drum and extending inwardly thereof, with a number of spaced apart heat transfer plates secured to corresponding strut elements.

A rotary drum dryer, comprising:

• an elongated, hollow drum having a moist product inlet and a spaced dried product outlet, with a drying chamber between the inlet and the outlet;
• fighting within said drum dividing the chamber into a plurality of drying stages along the length of the chamber, including a first stage adjacent said inlet, a final stage adjacent said outlet, and at least one intermediate stage between the first and the final stages,
• said intermediate stage including a plurality of drying zones arranged in successive order from a point proximal to said first stage and extending towards the final stage, each of said zones configured to define a heat transfer ratio calculated by dividing the total heat-transferring surface area within the zone by the volume of the zone,
• one of said zones proximal to said first stage having a heat transfer ratio of from about 1.5-2.5 ft−1,
• another of said zones closer to said final stage than said one zone having a heat transfer ratio from about 2.75-3.75 ft−1,
• said first stage including heat transfer fighting comprising a number of circumferentially spaced apart generally L-shaped numbers secured to said drum and extending inwardly thereof, each of said L-shaped members including a first leg secured to said drum and a second leg oriented at an angle relative to said first leg.

A rotary drum dryer, comprising:

• an elongated, hollow drum having an internal surface and a center area, said drum being provided with a moist product inlet and a spaced dried product outlet, with a drying chamber between the inlet and the outlet;
• flighting within said drum dividing the chamber into a plurality of drying stages along the length of the chamber, including a first stage adjacent said inlet, a final stage adjacent said outlet, and at least one intermediate stage between the first and the final stages,
• said intermediate stage including a plurality of drying zones arranged in successive order from a point proximal to said first stage and extending towards the final stage, each of said zones being provided with a plurality of radially disposed, circumferentially spaced fighting members extending from the center area of the drum to said internal surface thereof, each pair of adjacent fighting members presenting a product passage therebetween, the product passages of each zone being in direct, substantially unimpeded communication with the passages of the next adjacent zone, said fighting members being configured and arranged to present a heat transfer ratio calculated by dividing the total heat-transferring surface area within the zone by the volume of the zone,
• one of said zones proximal to said first stage having a sufficient number of said fighting members to define a heat transfer ratio of from about 1.5-2.5 ft−1,
• another of said zones closer to said final stage than said one zone having a greater number of said fighting members than the number of fighting members in said one zone and defining a heat transfer ratio from about 2.75-3.75 ft−1.