Ethylene polyethylene plant safety 1

[michaelrishi]

Hi
Are there any particular safety issues that surround ethylene manufacturing plants ?

 

[epoisses]

Are you talking about ethylene manufacturing (steam cracking) or polyethylene manufacturing? The issues are quite different.

 

[JLSeagull]

Many safety related issues in an olefins complex are the same as other hydrocarbon processing facilities.

Many specifications for wetted components in ethylene manufacturing prohibit the use of copper or copper compounds. This may be due to the adverse reaction of copper with acetylene, a potential byproduct during the cracking stage or hot end of the unit.

 

[dcasto]

Ethylene and Ethyne (accetylene) have a unique property called decomposition. The ethylene molecule will decompose into a C-C and 2 H2 molecules. This reaction is exothermic and creates 3 gas molecules for each 1 ethylene molecule. Because you have heat released and a trippleing of the pressure, it is quite explosive in nature.

The point at which a ethylene molecule decomposes has been studied and I know if you research decomposition you can get all the details. There are some charts on what temperatur and pressure this happens, but on the safe side at 800 psig we kept the temperature below 600 F and at 2000 psig under 400 F, you could draw a straight line between them. Acetylene is even worse or will decompose at lower energy levels. As JLS indicated, copper and other metals can act as a catalyst and change the the point that a decomposition occurs, so they are advoided.

Interesting too, ethylene will also spontaneously polymerize with the right catalyst at normal temperatures and pressures. A great cataylst for this is FeO (with the proper number of each). The reaction is not fast and they only side effect is cleaning out plastic from time to time.

 

[michaelrishi]

I am talking about steam cracking of ethylene and polyethylene manufacture by liquid slurry reaction and gas phase reaction. Are there any hazards or past incidences which occurred on other ethylene and polyethylene plants around the world ?