RO System Eliminates Caustic Chemicals, Saves $150,000
Wax manufacturer selects 150 gpm RO system to pretreat incoming city water, which feeds plant’s steam boiler system
The International Group, Inc. (IGI) is a manufacturer of petroleum wax-based products in Toronto, ON, Canada. IGI paraffin waxes can be found in products ranging from candles to crayons and lipsticks to labels. Known for its commitment to preserving the environment, IGI has established many high-level technical projects to address the problems of waste utilization and the impact of products on the environment.
William McQuade, plant manager, recently set an objective to improve the plant’s pre-treatment of incoming city water, which feeds the company’s steam boiler system. In addition to reducing the waste disposal of the water treatment chemicals and the amount of boiler blow down water, McQuade was also looking for a cost-effective and environmentally safe solution.
The existing ion exchange systems used by IGI consisted of concentrated sulphuric acid and sodium hydroxide. These chemicals posed significant safety concerns, such as acid spillage and salt corrosion, when stored on-site. Further-more, the chemicals caused dramatic swings in the plant’s effluent pH as they were sent to drain, making it difficult to maintain a neutral pH in the effluent.
McQuade wanted to discontinue the use of sulphuric acid and sodium hydroxide for the ion exchange systems in the boiler room and improve on the steam boiler system’s efficiency. Because IGI’s steam plant produces approximately 1.5 million lbs of steam per day, seven days per week, 363 days per year, it was apparent that the cost savings could be dramatic.
Ultimately, IGI needed a reliable system that would reduce operating costs, make the boiler room a safer place to work, and, most importantly, reduce the amount of chemicals the company was using in the boiler room and sending to the sewer each year.
In order to improve the efficiency of the boilers, obtain a high costs savings on fuel, and achieve clean steam production, IGI turned to GE Infrastructure, Water & Process Technologies (GE). The company designed a 150 gpm RO system for IGI. The RO process, in which solutions are desalted or concentrated using relatively high hydraulic pressure as the driving force, rejects salt ions and other
contaminants using pressure to force pure water through the membrane. This purer RO water allows the boilers to operate at higher cycles. With the old ion exchange systems, the boilers operated at 10 cycles, which corresponds to 10% blow down. With the new RO system, the same boilers operate at 100 cycles, with only 1% blow down rate.
During installation, the design team was faced with a limited amount of space, and the existing ion exchange systems needed to be removed to house the new RO system. Detailed floor plans were made and some minor civil work was done to fit the new system in its final location. In order to keep the steam plant fully operational while the ion exchange systems were removed and RO system commissioned, the water treatment program was modified appropriately.
Monitored 24 hours per day, the RO system currently pretreats the incoming city water, prior to the water being fed to the steam boiler system. The RO removes 98% of the dissolved minerals in the city water, allowing the steam boilers to operate at 100 cycles of concentration. GE chemically treats the steam boilers, various cooling water systems, the closed systems and certain process streams within the refinery.
The RO system was installed with a complete backup water supply. A city water bypass valve automatically supplies water to the RO permeate tank anytime the system is offline for maintenance or during abnormally high steam load requirements.
The RO system has been an unmitigated success. After one year of operation, not only has the RO system reduced IGI’s boiler system operating costs by more than $150,000 per year by increasing the steam boiler’s efficiency over 3%, but it has also completely eliminated the use of sulphuric acid and caustic in the boiler room. Additionally, it has reduced the amount of boiler blow down by 90% and reduced the salt discharged to the sanitary sewer by the steam plant water softeners 70 times the previous amount.
The system has proven to be very reliable, and has been offline less than 1% of the time for maintenance, filter changes and membrane cleanings since the installation. In addition, the system has never allowed the boiler feed tank water to reach a low level.
Bill McQuade said, “GE Infrastructure, Water & Process Technology has followed through on this project from the very beginning to the end. They identified the savings for us, made sure all of our concerns were addressed, and walked us through the process every step of the way.” wqp