Over the years, we’ve come to expect our water source to be safe, convenient, and inexpensive. After all, our municipal water treatment plant just pumps it from the ground or from a river, puts a little chlorine in it, and sends it on…right? Wrong.
Water, when it comes to using in our taps, is a manufactured product, often involving multiple steps for it to be safe for us to drink and less harmful to transmission lines and pumping equipment. However, potable water is no necessarily acceptable for use in boilers and cooling towers because of dissolved minerals and/or gases that can damage equipment. While it’s true that chemical treatment of industrial process water is necessary and beneficial, it can also strain the budget of the most frugal maintenance engineer. At that point, it may become necessary to invest in other pre- treatment equipment more capable of removing objectionable materials before they have the opportunity to wreak havoc in a boiler system.
Industrial Pre-Treatment Processes
Engineers have been designing pre-treatment equipment in varying degrees of sophistication for a century. With new technologies becoming available, the water treatment industry is now moving very quickly to develop versatile equipment capable of removing as much (or as little) dissolved solids from water as is desired or required. Industrial pre-treatment equipment falls into four broad categories: Filters, Softeners, Reverse Osmosis, and Deionization. Depending on many factors determined by water analysis of your make up source, one or more of these processes may be necessary to adequately remove the offending solids.
Often used to remove chlorine, iron, manganese, suspended solids, or other materials that may interfere with a secondary pre-treatment step (such as reverse osmosis or deionization). Filters can be made from many different materials and are adaptable to numerous operational modes.
Water softeners are the most prevalent of all ion exchange mediums, removing calcium hardness ions and replacing them with non-offensive sodium ions. Long an industry standard, they offer no relief for high total dissolved solids levels which causes blowdown requirements to increase.
Reverse osmosis is a process by which water is forced through a semi permeable membrane, removing 90 to 95% of all dissolved solids contained therein. The effluent (permeate) is highly desirable as boiler make up. It contains only a small percentage of carbonate alkalinity that would normally flash to carbon dioxide in the steam, thereby reducing the amount of neutralizing amines necessary for pH adjustment of the condensate. However, the biggest advantage to reverse osmosis is the extreme reduction of total dissolved solids (TDS), saving energy by drastically reducing blow-down requirements. Often the equipment will pay for itself in terms of energy savings alone.
Industrial deionization processes normally consist of passing the water through vessels filled with cationic and anionic resins to remove 99+% of all TDS. Like softeners, they require periodic regeneration, only with acid and caustic soda instead of salt. For boilers operating at less than 400 psig this step is usually not desirable due to the higher maintenance time and expense. Pre-treatment technology is now available and cost effective. If you’d like to learn more about how your plant can take advantage of it, contact Walter Louis Fluid Technologies.