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Ethylene Glycol Refining System

Brief Overview

The 8 year old skid mounted Ethylene Glycol Refining Plant was designed by Koch/ Glistsch Systems and was previously operated by DuPont. It can be moved and re-erected at a very low cost. The major components of the Ethylene Glycol Refining Plant are a Buss wiped film evaporator (183 sq. ft), and a Glitsch distillation column with three packed sections. The system was previously used to recover ethylene glycol for re-use in a polyester resin manufacturing process.

Capacity:

5500 lbs/hr
 

Technology:

Koch/Glitsch
 

Built:

1995
 

Shut Down:

2002
 

Documentation:

Available
 

Major Equipment:

- Buss Wiped Film Evaporator (183 Sq. Ft/17 Sq. Meters)
- Distillation Column

Process Description

General Process Description
Contaminated ethylene glycol, external to the Glitsch system, is fed to the feed preheater (E-1). This liquid is heated from 25C to 115.6C @14.5 psig using steam. The preheater feed flows to the wiped film evaporator (EV-1) where it flashes to 50mmHg Abs. Additional heat is added through the evaporator jacket using steam. The bottom from the evaporator flows to the sludge receiver (T-1) by gravity where it is pumped out the Glitsch system to storage while 2.4 GPM are recycled to the evaporator using the sludge pump (P-1). The vapors from the evaporator are fed to the distillation column (C-1).

The distillation column has three packed sections; a pasteurization section above the sidedraw, a rectifying section above the feed, and a stripping section below the feed. Heat is supplied to the column via a steam heated shell and tube type reboiler (E-5). Ethylene glycol vapors, ascending the pasteurization section, remove the light ends from the descending liquid. Overhead vapors from the column are partially condensed in the partial condenser (E-2), against temperate cooling water. The condensate, mostly ethylene glycol, flows by gravity as reflux to the column. Diethylene glycol vapors, ascending the stripping section, remove ethylene glycol from the descending liquid. The diethylene glycol vapors ascending the rectifying section are removed by the descending ethylene glycol liquid from the pasteurization section. The ethylene glycol liquid is partially drawn and pumped out of the Glitsch system via the product pump (P-3) throughout the refined glycol cooler (E-3). Diethylene glycol from the bottom of the distillation column is pumped out of the system via the bottoms pump (P-5). The light ends are drawn from the system as non-condensed vapors in the overhead partial condenser.

The non-condensed vapors, mostly light ends, are further condensed in the cold trap (E-4), against 60F service water. The vapors from the cold trap are sucked into the vacuum system. The steam is used to create vacuum in the ejectors (J-1 and J-2) scrubs out the remaining light ends from the non condensed vapors. Condensate from the cold trap is combined with liquid from the vacuum system and pumped out the Glitsch system using the light ends (P-4) to the steam boiler (external to the Glitsch system).