Friday, 24 May 2013

Recommended safe storage Practices

Ignition sources such, as static electricity must be avoided. Bonding and grounding can prevent static electricity. Emergency cooling by firewater sprays is used to avoid overheating of closed vessels. If acetylenic compounds are present, acetylide forming metals, such as copper and magnesium alloys are not used where they come in contact with ethylene oxide. The quantity of EO held in the plant area should be kept to a minimum. Bulk storage facilities for EO should be remote from operating plants with provision for easy fire fighting access. Storage tanks must be periodically cleaned to remove accumulated polymers and other foreign matters.
14.2 Safety Review of Loop Reactor R 301
Normal operating procedures:
·        The catalyst is fed into the solvent ethylene carbonate, which is then fed into the reactor.
·        Reaction is carried out under 15-bar pressure. Moreover EO vapours are inflammable. Hence the reactor should be operated either below LFL or above UFL of EO-air mixture. Inerting is done to reduce the concentration of oxygen below LOC. So vacuum purging is done.
Procedure for vacuum purging
    1. Drawing a vacuum on the vessel until the desired vacuum is reached.
    2. Relieving the vacuum with an inert gas such as CO2
    3. The above two steps are done until the desired O2 concentration is reached.
  • CO2  sparging is done through the riser. As a result liquid circulation starts.
  • Once the liquid circulation gets stabilized, CO2 sparging is stopped in the riser and started in the downcomer.
  • Cooling water circulation is started in the plate heat exchanger.
  • Ethylene carbonate is removed from the top disengagement tank.

Safety procedures

  • Reactor is provided with same type of safety control as provided for the
EO storage tank.
  • CO2 compressor, cooling water supply in plate heat exchanger should be kept in emergency power supply.

Safe shut down procedure

  • EO sparging is stopped
  • CO2 sparging is stopped
  • Cooling water circulation in the plate heat exchanger is maintained.

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