DISTILLATION PROCESS

The “Donkey” still is designed to reduce the maintenance / clean-out schedule of the main on-line process distillation system. In a typical vapor degreasing system that is subjected to heavy oils, greases, or contaminants in production loading; the main distillation system(s) is on stream continuously to remove the contaminants from the degreaser tank, distill the dirty solvent, and return the clean solvent back to the degreaser so the production work is exposed to the cleanest solvent possible.

Based on the amount of contaminants being introduced into the degreaser, which is then removed by the still, the solvent in the distillation system will become loaded with these contaminants to a level where the amount of clean distilled solvent being returned to the degreaser is greatly decreased. At this point in time, the main distillation system must be cooked down and properly cleaned. This action requires maintenance time, produces still bottom waste which must be properly disposed of, and takes the main distillation system off-line while being maintained.

To reduce the clean-out frequency of the main distillation system, the “Donkey” still is used to pull contaminated solvent from the main still bottom. The “Donkey” still is designed for lower solvent distillation rates as well as holding less volume once cooked down. These design features allow the main still to remain on stream for longer intervals while the “Donkey” still can be taken off line, cleaned very quickly / easily based on tank design, returned to operation, and the amount of actual still bottom waste is considerable less than the amount which would be generated by the larger main distillation system. This equates to cost savings!

A key design feature is the tank bottom and heating mechanism. The “Donkey” still is designed with the tank floor installed on a sharp downward angle toward the quick opening marine type clean-out door. This facilitates ease of drainage / clean-out.

The steam heat is provided to the tank from a steam jacketed bottom under the floor.

Optional hot oil with electric heaters can be supplied if desired. This means there is no heating device inside the still chamber to impede clean-out procedures. With the heat being external of the tank floor and isolated from the contaminated solvent, there are no heating elements or coils to clean. This greatly reduces maintenance time as well as potential replacement parts cost.

Contaminated solvent to be reclaimed is transferred into the “Donkey” still by means of a fluid displacement switch controlling a transfer pump. This pump will transfer contaminated solvent from the main distillation tank to the “Donkey” still. This solvent/contaminant mixture is heated to the solvent’s boiling point; thereby vaporizing the solvent present, freeing it from the contaminated portion of the mixture. Solvent vapors rise and condense on the internal cooling coils. The condensed solvent and any entrained moisture drains by gravity into the condenser troughs and flows through piping to an external water separator. Water is separated from the distilled solvent at this point based on retention time and temperature. The discharged solvent is returned by gravity to the degreaser for reuse.

The water separator outlet can be provided with an optional visaflow gauge so that the flow of distillate can be observed. This visaflow gauge is mounted in a convenient viewing place. Typical distilled solvent return to the degreaser is by gravity flow. When gravity return is not possible, an optional distillate receiver tank with transfer pump is recommended.

DISTILLATION PROCESS

The “Donkey” still is designed to reduce the maintenance / clean-out schedule of the main on-line process distillation system. In a typical vapor degreasing system that is subjected to heavy oils, greases, or contaminants in production loading; the main distillation system(s) is on stream continuously to remove the contaminants from the degreaser tank, distill the dirty solvent, and return the clean solvent back to the degreaser so the production work is exposed to the cleanest solvent possible.

Based on the amount of contaminants being introduced into the degreaser, which is then removed by the still, the solvent in the distillation system will become loaded with these contaminants to a level where the amount of clean distilled solvent being returned to the degreaser is greatly decreased. At this point in time, the main distillation system must be cooked down and properly cleaned. This action requires maintenance time, produces still bottom waste which must be properly disposed of, and takes the main distillation system off-line while being maintained.

To reduce the clean-out frequency of the main distillation system, the “Donkey” still is used to pull contaminated solvent from the main still bottom. The “Donkey” still is designed for lower solvent distillation rates as well as holding less volume once cooked down. These design features allow the main still to remain on stream for longer intervals while the “Donkey” still can be taken off line, cleaned very quickly / easily based on tank design, returned to operation, and the amount of actual still bottom waste is considerable less than the amount which would be generated by the larger main distillation system. This equates to cost savings!

A key design feature is the tank bottom and heating mechanism. The “Donkey” still is designed with the tank floor installed on a sharp downward angle toward the quick opening marine type clean-out door. This facilitates ease of drainage / clean-out.

The steam heat is provided to the tank from a steam jacketed bottom under the floor.

Optional hot oil with electric heaters can be supplied if desired. This means there is no heating device inside the still chamber to impede clean-out procedures. With the heat being external of the tank floor and isolated from the contaminated solvent, there are no heating elements or coils to clean. This greatly reduces maintenance time as well as potential replacement parts cost.

Contaminated solvent to be reclaimed is transferred into the “Donkey” still by means of a fluid displacement switch controlling a transfer pump. This pump will transfer contaminated solvent from the main distillation tank to the “Donkey” still. This solvent/contaminant mixture is heated to the solvent’s boiling point; thereby vaporizing the solvent present, freeing it from the contaminated portion of the mixture. Solvent vapors rise and condense on the internal cooling coils. The condensed solvent and any entrained moisture drains by gravity into the condenser troughs and flows through piping to an external water separator. Water is separated from the distilled solvent at this point based on retention time and temperature. The discharged solvent is returned by gravity to the degreaser for reuse.

The water separator outlet can be provided with an optional visaflow gauge so that the flow of distillate can be observed. This visaflow gauge is mounted in a convenient viewing place. Typical distilled solvent return to the degreaser is by gravity flow. When gravity return is not possible, an optional distillate receiver tank with transfer pump is recommended.