Most evaporator applications in rendering use waste heat -- usually vapors from a continuous cooker or dryer. Common
applications include the concentration of waste water streams or water pressed from hydrolyzed feathers, the drying of restaurant grease, and the evaporation of water from raw material. In some rendering systems, evaporators are used as cookers. Typical systems include:
Retrofit Evaporator System This system uses the waste heat in the cooking vapors of a continuous system. The waste heat removes water from raw material under vacuum, increasing system capacity and steam efficiency. The system employs a Preheator, Drainor and Prepressor to provide the evaporator’s feed stream. Evaporator discharge joins solids from the Prepressor in a Supercookor for finish cooking.
Dupps Thermsavor™ System Raw material — finely ground and fluidized with recycled fat — is the feed stream for this double-effect evaporator system which cooks the material under vacuum before fat/solids separation. The use of waste heat improves steam efficiency over conventional single cooker continuous systems. Low temperature operation insures top-quality product. Third effect options are available.
Dupps Grease System This system uses an evaporator to remove water from restaurant grease. The heat source can be live steam or waste heat from a cooker. Dry grease from the evaporator is fed to a decanter-type centrifuge for solids removal, and is then ready for storage. State-of-the-art controls help maintain superior product quality. Evaporator system schematic
Common types of evaporators . . .
• A conventional falling film evaporator is suitable for non-fouling applications where tube coating is not a problem. A vertical shell and tube heat exchanger is mounted directly above an integral vapor separator. Evaporator liquid is circulated through the tubes by a pump beneath the vapor separator. The heat source is on the shell side of the heat exchanger.
• In a rising film evaporator, the heat exchanger is mounted vertically and the evaporator liquid flows upward through the tubes. Temperature in the evaporator liquid builds as the liquid rises. This boiling action helps force liquid up and out of the tubes. The liquid and vapor leave the heat exchanger together and enter the vapor body. After vapor separation, remaining liquid flows from the vapor body through the circulating pump to the heat exchanger.
• For applications where tube coating is a problem, the preferred choice is a forced circulation flash evaporator. The main components are a horizontal shell and tube heat exchanger, a flash chamber mounted above the heat exchanger, and a circulating pump. Evaporator liquid circulates through the heat exchanger tubes at high velocity to inhibit coating and enhance heat transfer. The heat source is on the shell side of the heat exchanger. Liquid from the heat exchanger enters the flash chamber where water is flashed off. Since there is no coating in the heat exchanger, evaporator performance remains constant without expensive cleaning procedures. More . . .
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