Cracking furnace valves
The cracking furnace section of a steam cracker
includes valves for controlling the supply of
feedstock, with each pass having its own control
valve.
The fuel gas/oil section has two isolation emergency
shutdown (ESD) valves and an emergency safety
vent (ESV) valve located between these, in what
is called a “double isolation and bleed” setup. A
control valve follows the second ESD valve. At least
one ESD shut-off line is present, but most modern
safety regulations require redundant lines to ensure
operation in case of a malfunction. Finally there are
also separate shut-off valves for each burner.
In addition, dilution steam is also on flow control.
There may either be a single valve present
controlling the total flow of dilution steam, or each
pass may have a control valve of its own.
Following the transfer line exchanger, a transfer
line valve (TLV) and a decoking line valve (DLV) are
present, one of which is open and the other one
closed depending on whether the furnace is in
operation or is being decoked.