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Vitamin E Plant

Brief Overview

The plant was originally designed and constructed in 1997. Production began in February-1998. Over the next several years, production increased from an initial capacity of 1500 metric tons per year to 2250 mtpy. To meet changing market requirements, a high vacuum distillation train was added in 2000. This increased product purity from 98 % to 99.4%. Due to failing market conditions, operations ceased in August 2001. The plant equipment was flushed with a solvent, and then water washed and drained. It has been idled since that time.
 

Capacity:

1500 -  2250 metric tons per year
 

Built:

1997
 

Shut Down:

2001
 

Major Upgrades:

2000 a high vacuum distillation train was added
 

Major Equipment:

Five main functional areas:

1. Reaction
2. Refining
3. Utilities
4. Storage
5. Receiving
6. Packaging and Shipment

Due to the multi-step process, there are numerous pieces of process and utility equipment. Due to the corrosive nature of many of the chemicals involved, the equipment is a combination of 316 ss, 316t. ss, Hastelloy C, graphite, PTFE, and FRP.

- (2) Distillation columns, 8 ft. dia. X 40 ft. OAL
- (6) Evaporators
- (43) Heat Exchangers
- (19) Filters and Dust Collectors
- (70) Pumps
- (2) Reactors with Agitators
- (61) Miscellaneous tanks and vessels, seven with agitators
- (14) Vacuum pumps or booster pumps
- (1) Scrubber
- (1) Clarifier
- (2) Solids Discharge Systems
- (1) Packaged Boiler with Treatment Systems
- (3) Chillers
- (1) Cooling Tower
- (9) Hot '011 Heaters
- (2) Air Compressors with Desiccant Dryers

 

Process Description

Synthetic Vitamin E Manufacturing
Alpha-tocopherol, or Vitamin E, is an alcohol derived from isophytol and trimethyl hydroquinone (TMH - C9H1202). This plant was designed to produce synthetic (dl-alpha tocopherol), not natural Vitamin E (mixed, containing d-alpha tocopherols). The Vitamin E was produced for both human (nutrition and cosmetics personal care -both FDA regulated) and animal feed (USDA regulated) markets. Each product had somewhat different specifications and modes of packing and shipment_ Production was split about 65/35 between human/animal products. Although it was not required, the facility was operated per cGMP procedures.

Raw materials were received at the northwest side of the plant and stored in a tank farm or in the warehouse. Raw materials received included isophytal (isatsiners), TMH (IBC's in solid form), zinc chloride (supersacks), zinc dust (30 gal. fiber drums), HCI (tank trailer), acetic anhydride (tank trailer), and diethyl carbonate (tank trailer).

The process reacted TMH with isophytol with 800-950 kg/day of ZnCI catalyst in a 3200 gal, glass-lined reactor. About 50 kg/day of Zn powder was used as a reducing agent. This batch reaction took 18 - 20 hours, The material was then fed to a second 3000 gal. glass-lined reactor where acetic anhydride was added to stabilize the Vitamin E in another 18 hour batch reaction. Small amounts of HCI and caustic were also added in these reactors as a catalyst and for pH control respectively.

Following the reaction steps, the product was fed to a continuous distillation system to increase product purity. The initial distillation system consisted of a Ketema falling film evaporator, Buss thin film evaporator, two Buss wiped film evaporators, and associated vacuum systems, condensers, and receivers.

To increase product purity, a continuous distillation system was added comprised of two large, packed (Koch BX packing) distillation columns with Pfaudler wiped film evaporators as reboilers.

Two of the Buss units were mothballed. Currently, the plant distillation capacity is; twice the reaction system capacity. The process had about 85 -90% conversion of feeds. The two types of byproducts were TMHdiacetate (a solid that sublimes at higher temperatures) and other heavies (dimmers). These were left in or mixed back into, animal feeds, but were removed from human use product.

Products from the distillation process were stored in 8000 gal. SS vessels prior to packaging. Products were packaged In 15 gal. or 25 gal. drums, 900 kg totes, and by tank trailer. Separate automatic filling machines were used for animal and human products. Limited product storage capability exists on site. The process was controlled by a PLC-based control system with operator CRT screens.

Utilities
A 150 HP packaged steam boiler produced 160-psig utility steam for heating and tracing. A total of three packaged chiller systems produced 40-50 °F and 60-70 °F chilled water. The plant site has a 8 MBtu /hr cooling tower for process cooling water. Nitrogen was provided by a leased evaporation system. Two air compressors with desiccant dryers provided 90 psig compressed and instrument air. An electric hot oil system provided process heat for the distillation area. A small amount of electric heat tracing was used.

For air emissions, the plant was not required to file formal permits, just notifications per the Texas "Permit-By-Rule" system. A small water scrubber provided limited air emissions control. Wastewater was impounded and pH adjustments were made as necessary prior to pumping to Gulf Coast for treatment. Small amounts of solid wastes were collected and disposed of through licensed contractors. Firewater is provided by a plant ring main supplied by a firewater tank and diesel fire pumps. The process plant has both wet and dry type sprinkler systems,