Macro 36
Centrifugal Distillation Still

The Myers Macro-36 Centrifugal Molecular Still is intended for production of high-vacuum distillation of heat sensitive organic compounds.

With over fifty years of experience in the design and manufacturing of Centrifugal Molecular Stills, Myers can offer unique qualifications for supplying the system to our customers requirements.

The MYERS Macro-36 Centrifugal Molecular Still is designed for throughputs from 100-400 pounds per hour depending upon feed material characteristics.

The material is pumped into the center of the heated rotating disk housed in a vacuum chamber. The feed material is spread by centrifugal force in a thin film across the face of the rotor. Film thickness is in the order of 0.010-.100 inches (.0025 -.025 mm), depending on viscosity, feed rate, etc.

The surface area increases exponentially as the material travels to outer circumference decreasing film thickness and exposing more molecules to surface for evaporation.

By close temperature control of heaters, the lighter, lower molecular weight, fraction of the feed material evaporates and condenses on the internal water-cooled condenser.

The heavier un-evaporated residue slides off the rotor into a collecting gutter; both fractions flow by gravity to discharge pumps and are transferred out of the still. The lower pressure developed by the vacuum pumps, reduces the boiling point of the material. This lowered pressure combined with the exponentially increasing surface area distills material at the most efficient rate per area of distilling surface, requiring less surface area per volume of production than other technologies and reducing the chance of thermal decomposition.

The following specifications cover the complete equipment requirement for a Macro-36 molecular distillation plant, exclusive of process piping.

Heating - Condensing Surface
The evaporating surface on the MYERS Macro-36 is that of a 36-inch diameter, 25° cone. Because this cone is rotating at 350 RPM, the average centrifugal unit force spreading the fluid feed is 40 "g". This gives an effective evaporative surface, which is greater than that of other types of equipment of equal actual area.

Performance Specifications
The MYERS Macro-36 Centrifugal Molecular Still is sized to accept up to 400 pounds per hour (dependent upon feed material characteristics) of degassed feed material on to the center of a 36-inch diameter heated spinning rotor within a concentric dished vacuum chamber. At a rotor speed of 350 R.P.M., the distilland mixture becomes a thin film by centrifugal force. The resultant film, whose thickness and speed are controlled by feed rate, radiates to the edge of the rotor.

Three separate electrically controlled heaters behind the rotor evaporate the lower boiling fraction of the material. The distillate condenses on the water-cooled dished head condenser. The un-evaporated liquid residue slides off the rotor into a concentric collecting gutter. Both distillate and residue gravitate through connecting pipelines to vacuum- sealed positive liquid gear pumps and discharge from the still to atmosphere. Vacuum equipment maintains operating pressures of 1-20 X 10^-3 Torr in the still at maximum feed rates. The ultimate pressure of the Macro-36 molecular still is to be 1 X 10^-4 Torr, clean, dry, and empty.

Operating Objectives
Feed material should be degassed to remove all but a few percent of low boiling volatiles. These volatiles may be condensed if desired or eliminated. A degasser will permit maximum reduction of low boiling volatiles. Incomplete degassing is the major limiting factor to maximum feed rates to the molecular still. Actual unit performance can be estimated with a test run on a MYERS Lab-3 Centrifugal Molecular Still.

Still Assembly
The still chamber is comprised of a 300 series stainless steel base plate set at a 45° angle on a welded steel frame and a top- hinged stainless steel water-cooled dome. The base plate has a pumping port with a rear flange that mates to the vacuum pump though a multi-coolant trap which provides for entrapment separation and protection of pumping system. Centered on the base plate is the conical 36-inch diameter stainless steel rotor driven though a water-cooled vacuum feed-through.

Behind the rotor are three independently wired heater elements, which allow precise temperature control of rotor area with solid state power controls. They are insulated from the base plate by baffles. A stainless steel water-cooled dome condenser is vacuum flanged to the base plate. Two sight glass viewing ports are provided in the condenser dome. Three lift hooks permit the customer's hoist to open the still dome for cleaning and maintenance.

The feed material is pumped from the de-gasser to the center of the heated spinning rotor. Distillate condenses upon the inner surface of the water-cooled condenser dome, and by gravity, passes through the bottom of the base plate to the distillate liquid gear pump. The unevaporated residue slides into a stainless steel gutter along the edge of the rotor and proceeds by gravity to a residue liquid gear pump.

A liquid gear pump is provided for overflow and drip, which may be combined with the residue or distillate. The distillate product, drip and residue lines are series 300 series stainless steel. Liquid transfer lines are fitted with check valves that allow continuous feed/discharge to and from still from/to atmosphere. All surfaces in contact with process material are series 300 series stainless steel.

Direct-drive liquid-transfer pumps with variable speed motors for the rotor feed, distillate, residue and drip

Glass flow meters are installed in residue, distillate, and drip lines to observe flow and set gear pump speed.

Valve panel and plumbing provided for cooling water flow control for components.

Control Center
The instrument control panel/distribution center contains the following controls:

• Power distribution cabinet with disconnect
• Circuit protection for motors, heaters, pumps, etc.
• Front panel schematic of system with controls located for ease of operation.
• Lighted switches to show component status.
• Thermistor vacuum gauges (with leak detect function) to indicate pressure in the still and
  in the foreline.
• Closed loop temperature controllers, also capable of percent power operation, with solid
  state power controls for control of three Rotor heat zones and digital display of set and actual
  temperature of each zone.
• Thermocouples with digital display is supplied at the rotor residue outlet

Vacuum Pumping System
The Vacuum Pumping System of the Macro-36 Centrifugal Molecular is a combination oil booster and mechanical pump. The High vacuum pump is the Myers KSM-2000 rated at 2500 liters/Minute in the 10^-3 Torr pressure range. The Pumping System is supplied with necessary gaskets at vacuum connections to the Macro-36 still.

Installation-Maintenance
Basic reqiurments

• Height required to raise rotor: 8' 6"
• Weight - estimated 3800 pounds
• Electrical - 40 KW at 208V, 50/60 Hz, 3 phase.
• Water - 13 gallons per minute at 20°C maximum.

Myers staff of skilled Engineers are available to provide installation, maintenance and training of operators and support personnel.

Options

Degasser spray/falling film

• Controls - Closed loop temperature controllers, also capable of percent power operation, with solid state power controls for control zones and digital display of set and actual temperature of each zone for the degasser
• Direct-drive liquid transfer pumps (degasser feed) with variable speed motors. Manually activated on-off via button with indicator status lights on the control panel.
• 300 series degasser chamber with bands and thermal covers
• Multi-coolant trap which provides for entrainment separation and protection of pumping system.
• Mechanical Roughing pump
• Thermistor vacuum gauge, with leak detect function, to indicate pressure in the degasser chambers.

Line heaters - All interconnecting process piping can be electrically heat- traced with closed loop\percent power temperature control

Additional condensing area - Extra traps can be added to vacuum line in series with main traps in chamber or optional degasser.

Flow Meter - A digital flow meter can be installed in any of the fluid flow locations to accurately measure/adjust the feed/outputs of the still. Information on intended product viscosity and temperature at these points are required to specify or end-user provides.

Space and Utility Requirements

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