Municipal Water Treatment
Weighing ton containers containing chlorine for water treatment
The Alexandria Water General Authority in Alexandria, Egypt wanted to upgrade and rehabilitate seven (7) water treatment plants serving the city of Alexandria and nearby districts. A key component of the project involved replacing aging gas chlorination systems with a new centralized liquefied gas chlorination system. The new system would continue to utilize ton chlorine containers (cylinders) to supply the liquid to evaporators and gas dosing units.
The goal was to improve the consistency of the chlorine levels in the municipal water system. Weighing accuracy was a major concern as the current system relied on crane hung balances to weigh ton chlorine containers resulting in inaccurate dosing of chlorine and varying disinfection levels throughout the the water supply.
Operational efficiency was also a concern as on/off loading of the containers was both time consuming and hazardous. Each ton container weighed approximately 900 kg and the frequency of replacement required a cylinder to be on/off loaded every three (3) days.
Scaletron’s application engineers working in conjunction with their distributor, Bisan, Inc. in Ontario, Canada recommended the Scaletron Model 3001™ -3006™ Ton Cylinder Scale along with the Scaletron Model 1099™ Chemical Process Controller as an excellent solution to handle the weighing of the chlorine gas containers. Specifically designed for weighing corrosive chemicals, the Model 3001™ -3006™ features corrosion resistant construction and fully digital operation with the ability to weigh up to 4,000 lbs. (1814 kg) per base. This system would provide easy and safe on/off loading of containers and the ability to monitor multiple scale bases simultaneously with a single controller.
To meet the water authority’s needs, a total of 102 scale bases and 11 process controllers were installed. The scales were configured in banks, ranging from 2 banks of 2 scales each for the smaller water treatment plants to 4 banks of 6 scales each for the larger plants. Each bank of scale bases being controlled by a dedicated, multi-channel process controller that allowed up to 6 scale bases to be monitored per channel. By configuring the scales into banks, operational efficiency was improved as all containers in a bank could be replaced at once, rather than one at a time under the current system.
In addition, Scaletron Model 3000LB™ Lifting Bars were used in conjunction with new monorail crane systems for on/off loading of the ton containers onto the scale bases.
The new Scaletron weighing system enabled the Alexandria General Water Authority to meet its goal of improving the accuracy of the chlorination process and the consistency of the level of disinfectant in the municipal water supply. The scales allowed them to easily and accurately weigh multiple ton containers while the process controllers provided operators with convenient monitoring of the containers’ contents and allowed them sufficient time to prepare for their replacement. The system also gave them greater control over the entire chlorination process by offering insight on feed rates, consumption, time till empty, etc. that the operators did not have with the previous system.