We offer small lime dosing packages in 2 ways. Firstly with a constant transfer rate and we vary the solution strength in proportion to a 4-20 mA signal by varying the powder feeder. Secondly a constant solution is made up and a metering pump doses in proportion to a 4-20 mA signal.
.For both systems we always suggest the dosing line be kept as short as possible and to achieve this either the mains be close to the dosing pump or a booster transfer pump be installed to take water from the mains transfer it close to the dosing pump and return it back to the mains.
Lime will settle out whenever the dosing is stopped. With the constant transfer system, when the feeding of the lime powder has stopped, water is allowed to continue for a set period to flush the tank, pump and transfer line. With this system, the velocity in the transfer pipe is always at maximum helping to prevent lime settling out in the line.
With a batch make-up system it has to be decided as to what is to be flushed. Solenoid valves can be fitted to shut down the discharge from the solution tank, provide water to the metering pump for an adjustable time to flush the dosing line, but this does not clear the tank or the outlet solenoid valve. It may not be an option to completely flush the solution tank depending upon the volume of the tank.
Small lime plant
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For this constant solution package the metering pump will more than meet most turndown requirements
but when dosing low capacities there is the risk of a too slow velocity in the dosing line resulting in lime
settling out in the dosing line.
A typical varying solution strength constant transfer system would operate as follows:
A bag of powdered lime is placed on the open door of the bag loader and held in place by the retaining spear.
The bottom of the bag is then opened manually, with a knife and the door closed allowing the lime to fall into the hopper.
Heating pads and a vibrator are fitted to the hopper to keep the powder dry and to prevent bridging of the powder. The powder is metered into the solution tank via the powder feeder where it is mixed into the make-up water. A stirrer ensures the solution is thoroughly mixed before being transferred to the injection point.
For larger Lime Plants please refer to tomal.com.au