(BAT) Reference Document for the Production of Chlor-alkali ...
(BAT) Reference Document for the Production of Chlor-alkali ...
(BAT) Reference Document for the Production of Chlor-alkali ...
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Chapter 4<br />
Prevention <strong>of</strong> chlorine releases by a collection <strong>of</strong> chlorine releases during maintenance<br />
operation to <strong>the</strong> absorption unit, a correct warning <strong>for</strong> process deviations and<br />
irregularities.<br />
In a more general way, a good layout <strong>of</strong> <strong>the</strong> installation and provision <strong>for</strong> instant shutdown <strong>of</strong><br />
some compartments help to prevent domino-effects. Manual emergency push buttons which can<br />
be used by any <strong>of</strong> <strong>the</strong> site personnel on discovery <strong>of</strong> a chlorine leak should be present around <strong>the</strong><br />
plant.<br />
In <strong>the</strong> loading area<br />
In any liquid chlorine loading (or unloading) system, <strong>the</strong> weakest link is <strong>the</strong> connection between<br />
<strong>the</strong> static plant and <strong>the</strong> mobile tank. The use <strong>of</strong> pneumatic valves with automatic shut down in<br />
case <strong>of</strong> failure <strong>of</strong> <strong>the</strong> link, at both ends <strong>of</strong> <strong>the</strong> link, is essential to limit <strong>the</strong> leak.<br />
Only a risk assessment study, proper to each installation, can give <strong>the</strong> most likely modes <strong>of</strong><br />
failure during loading and <strong>the</strong> associated safety measures to avoid <strong>the</strong>m. Examples <strong>of</strong> some<br />
standard measures are:<br />
Improved chlorine detection and location and rapid isolation <strong>of</strong> sources feeding a leak<br />
Connection <strong>of</strong> loading area to a chlorine absorption system<br />
PTFE hoses should not be used (based on in<strong>for</strong>mation reported to accident databases)<br />
Articulated arms or correctly specified flexible hoses and coils <strong>for</strong> chlorine transfers<br />
Table 4.18: List <strong>of</strong> some preventative and corrective or emergency measures to avoid accidents<br />
at loading areas <strong>of</strong> a chlor-<strong>alkali</strong> plant<br />
Loading area hazards<br />
Tank overfill<br />
Tank over-pressurisation during<br />
filling<br />
Examples <strong>of</strong> preventative<br />
measures<br />
Overfilling protection <strong>of</strong><br />
<strong>the</strong> transport vehicle: a<br />
double weighing<br />
installation (two<br />
weighbridges operated<br />
by two different workers)<br />
should be installed<br />
Venting procedure to<br />
remove inert gases<br />
Examples <strong>of</strong> corrective or<br />
emergency measures<br />
Warning <strong>for</strong> loading<br />
deviations and<br />
irregularities<br />
Automatic<br />
shutdown<br />
pump<br />
<strong>Chlor</strong>ine detectors<br />
connected to alarms in<br />
<strong>the</strong> control room<br />
Remotely controlled<br />
shutdown valves<br />
Emergency procedures<br />
Supply pump can be<br />
tripped manually or from<br />
control room<br />
Moisture analysis in<br />
chlorine gas and padding<br />
gas, with alarm<br />
Response by process<br />
operators to evidence <strong>of</strong><br />
ferric chloride in valves<br />
Suction failure alarm in<br />
vent<br />
system<br />
gas scrubbing<br />
WORKING DRAFT IN PROGRESS<br />
Corrosion due to chlorine/water<br />
reaction<br />
Check tare weight <strong>of</strong><br />
tank<br />
Moisture control system<br />
and avoidance <strong>of</strong><br />
possible back-flow<br />
TB/EIPPCB/CAK_Draft_1 December 2011 219
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