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~± <br /> <br />Scrubber Solution Level <br />The level of sodium hydroxide solution in dhe scrubber <br />reservoir is maintained by the addition of process water via <br />valve HV437. A level probe LIT440 mounted in a stilling well <br />opens and closes the valve, and also alarms kjigh and low <br />( level conditions. An overflow prevents over-filling, and a <br />J drain valve is provided to empty the reservoir for <br />maintenance. <br />NaOH Flow Rate <br />A locally-indicating flow meter (Rotameter FI606) in the <br />Sodium Hydroxide Metering Pump discharge line shows NaOH <br />flow rate. The flow rate is set to the required value by <br />adjusting the stroke of the duty pump, <br />Scrubber Pressure Drop <br />A differential pressure gauge (PDI438) at t~e scrubber <br />indicates pressure drop across the packing. Abn rurally high <br />pressure drop indicates that the packing is fouled, and <br />requires cleaning. Expected pressure drop is;~.5" wc. <br />~_ .- <br />Scrubber Solution Hleed <br />A locally-indicating flow meter (Rotameter FI~43) in the <br />scrubber solution bleed line indicates bleed s lution flow <br />rate. The bleed is adjusted to the required low rate by <br />throttling a valve the in the bleed line. <br />Scrubber Solution Circulation Rate <br />A locally-indicating flow meter (Rotameter, FI439) is <br />located in the delivery line from the scrubber r circulation <br />pump. The design circulation rate is gp . <br />6.2 INTERLOCKS <br />Interlocks between equipment drives ensure safe Start-up and <br />d shutdown in the correct sequence. Equipment, in the pH <br />d Adjustment System is interlocked as follows: <br />pH Adjustment Tank Agitator (04-AG-09) <br />Normal Start - no requirements <br />Normal Stop - no interlocks <br />Fault Trip - alarm only (tank continues to be <br />1 agitated by sparge air). <br />pj/1481rp 012591 6-2 <br /> <br />