Replacement storage and process tanks (IVBO)

Purpose

For optimum safety and operational reliability, it is mandatory to replace storage and process tanks correctly and on time. At IVBO, both the iron-trichloride and hydrochloric acid storage tank and the flocculation tank were approaching the end of their service life.

Problem-solution

IVBO's household waste incinerator has been adapted to contemporary needs several times over the years, but both the iron-trichloride storage tank and the flocculation tank were nearing the end of their lifespans. As was the storage tank for hydrochloric acid used in other processes.

At the site, CGK replaced a total of three tanks, including engineering, contstruction and assembly and each with different concerns:

• Highly resistant flocculation tank
  • The water in the flocculation tank has temperatures of 60°C to 70°C, which requires extra attention to the materials used. To ensure sufficient resistance to both the high temperatures and the chemical load of the flocculant, the original tank in steel was replaced by one in polypropylene, with wall thicknesses of as much as 5 cm.
  • The 38 m3 tank is equipped with agitators for mixing the flocculant and the necessary connections for gravity drainage of the water to the clarifier. Both at the agitator on top of the tank, at a height of 4 m, and at the side discharge, we provided extra platforms at IVBO's request. This way, the various parts are easily accessible for maintenance in case of defects or blockages.

• Fibreglass-reinforced plastic storage tank for iron trichloride
  • Replacing the old GRP tank came a 43m3 double-walled one, fully prepared in CGK's workshop and equipped with all the necessary Vlarem sensors.
  • As IVBO's operations could not be stopped during the works, CGK mounted a temporary tank at another location and we connected it to the existing pump. After dismantling and adjusting the concrete containment, we were able to install, electrically connect and start up the new storage tank and pump. Finally, to completely clean and dispose of the temporary tank again.
  • The new tank was fitted on top with a manhole and a railing with access gate in GRP.

• Storage tank for hydrochloric acid
  • The hydrochloric acid storage tank was replaced in the same way as the GRP storage tank. We opted for a 43 m3 double-walled tank that was placed (also with the intervention of a temporary storage tank) in the same location as the original horizontal storage tank.
  • To neutralise the acid vapours, this tank is fitted with a chemical vapour lock and instead of one, three pumps are connected to it: a centrifugal pump for filling the tank on the one hand and two pumps in parallel for pumping the chemicals to the demin plant on the other. For operational reliability, one of the latter two acts as a back-up.