Spirotech Group has successfully completed another turnkey lime system upgrade for a UK water authority, the purpose of this particular project being to replace and upgrade the existing lime softening system – a type of water treatment used for water softening which uses the addition of limewater (calcium hydroxide) to remove hardness (calcium and magnesium) ions by precipitation.
Upgrade of existing silos and two new mix tanks
The water authority plant consists of two existing concrete storage silos, suitable for bulk tanker filling, which were upgraded with new ancillary equipment. Spirotech’s upgrade includes new level indication, pressure vacuum relief valves, filter units, pressure sensors and new silo filling control panels.
Spirotech’s Technical Director, Ben Morgan, explains the project in more detail –
Although a relatively straightforward project for Spirotech’s designers and engineers, the installation process was quite a challenge logistically as the new mix tanks and stocks were installed inside an existing building and the tanks needed to be skated in through a new opening created in the side of the building.
The lower cone section of each existing silo was replaced with a new mild steel cone section, complete with an aeration system to assist in material discharge, and each silo cone was fitted with a new screw conveyor to transfer lime powder directly to the mix tanks. A reversible screw conveyor was also provided to allow either silo to transfer to either mix tank, selected by opening or closing the pneumatically actuated valves for route selection.
The two new mix tanks were designed, manufactured and installed, and both fitted with a mixer/agitator, loadcell weighing system and filter unit. The mix tanks discharge through a new pumped transfer system consisting of two centrifugal pumps for transfer to three stock tanks. The mix tanks, which cycle alternately on a duty/standby basis, have been designed to produce a lime slurry of 10% calcium hydroxide content, which is diluted down to 5% calcium hydroxide content in the stock tanks.
Three new lime slurry stock tanks
The three new stock tanks were designed, manufactured and installed to take receipt of the 10% lime slurry being transferred from the two mix tanks. Once transferred to the stock tanks the lime slurry is then diluted down to 5% weight for weight, using pumped service water. Each stock tank is fitted with an agitator and loadcell weighing system and discharge through a new pumped transfer system consisting of two centrifugal pumps for transfer to the existing reactors and also to provide a recirculation system back to the stock tanks.
We’re very pleased to say that our team of engineers at Spirotech completed and successfully commissioned the project on what was a particularly tight schedule.
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