Acid Regeneration Plant (ARP)
ARP is a necessity to pickling line (PL) for it reuses hydrochloric acid and prevents pollution. It is complement of PL in a Cold Rolling Mill.
The main process brief description:
The waste pickle liquor, pre-concentrated by a Pre-concentrator, is sprayed at the inside top of the reactor (roaster). Combustion gases dry up droplets of sprayed acid. The FeCl2 decomposes as per the formula below:
2 FeCl2 + 2 H2O + 1/2 O2 = Fe2O3 + 4 HCl
The solid iron-oxide-particles fall down to the lower cone of the reactor in the form of powder and are discharged through a rotary valve.
The roast gases consisting of combustion gases, water vapor and hydrogen chloride leave the roaster at the top and pass through a cyclone which separates part of the entrained Fe2 O3 dust. The separated cyclone oxide is discharged through a rotary valve and fed back to the roaster.
The roast gas then enters the pre-concentrator, where it is cooled and cleaned by direct contact with the re-circulated acid and enters an absorption column.
To absorb the hydrogen chloride gas, de-mineralized water or rinse is fed to the top of the absorber where a nozzle distributes the water onto the packing of the absorber. In the counter-current flow, the hydrogen chloride content of the gas is absorbed thereby forming regenerated acid.
Acid Regeneration Plant:
WPL (waste pickled acid) entering the plant: 3000
Regenerated acid total HCl - content: approx. 190 -