Butyl Acrylate Storage Tank System Process Design

Project Synopsis

Project Summary

The client, a manufacturer of synthetic organic materials, was designing new process equipment for a planned expansion of their operations at their eastern US facility.  The expansion was for a scale-up of some of the client’s existing commercial production units. The quantities of raw materials and products processed in the planned new equipment is large enough to fall under OSHA’s Process Safety Management (PSM) oversight and standards.  As an element of this expansion process, the client plans on adding an outdoor storage tank to hold butyl acrylate, a vinyl monomer.

Process Engineering Associates, LLC (PROCESS) recently completed an FEL-2.5 Process Design Package and PHA in support of the expansion process. The scope in that work included process design for multiple reactor systems including product recovery and emissions control.  PROCESS also assisted in obtaining a permit from the applicable state environmental agency.  The work described here is a continuation of these previous efforts.

PROCESS’ scope for this effort was the process design of an outdoor butyl acrylate storage tank, a plate and frame heat exchanger designed to limit tank temperature, a feed/circulation pump, and a truck unloading station.  The main deliverables were a detailed P&ID, Process Control Description, Equipment List, and sizing of multiple relief devices.  Some design highlights are listed below.

The storage of butyl acrylate requires multiple redundant interlocks to avoid auto polymerization. Auto polymerization ultimately results in catastrophic failure of the tank. Some key items used in the design of the large-scale storage tank included:

• Use of insulation coupled with vinyl sheathing combined with use of a heat exchanger to maintain cool temperatures such that low vapor pressure is maintained.  A plate and frame exchanger was used due to very tight approach temperatures.
• Lean air blanket was used as a polymerization inhibitor.
• Redundant safeguards were provided to prevent overheating of the circulation/feed pump.  A high temperature interlock and a low discharge flow interlock were specified.
• Three redundant tank temperature indicators were specified and arranged at equal intervals around the tank.  Remote readout and recording devices were specified such that any increasing temperature trend can be detected.
• Flame arrestors were located on all process vent lines.
• Measures were taken to reduce risk of static electricity build up inside the tank including a fill line dip pipe and low-level interlock to prevent recirculation through the mixing eductor when it is not completely submerged.
• A re-stabilization “short stop” system that allows for rapid addition of stabilizer to the tank was specified.

Industry Type

Utilized Skills

• Process design
• Specification of process safety related systems, equipment, and instrumentation.