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Boiler Feed Water Demineralization There are myriad applications of boilers worldwide, and boilers are inherently very valuable, critical, and important elements of the industrial production cycles in which they are embedded. Boilers lie in critical path positions at the upstream end of industrial or electric generation processes. Without the steam raised in boilers, industrial process and electric generators simply will not run. As examples, boilers are critical in food processing, crude oil refining, petrochemical plants, and other industrial processes, not to mention the thousands of small boilers that supply heat for office and industrial buildings. The effective operation of those boilers is critical to the proper operation, on stream factor, and profitability of industrial plants. There is zero flexibility with boilers; they absolutely must work and they must work 100 percent of the time without fail. Boilers are typically very high flow rate devices; they typically process a huge quantity of water in a day, week, month, or year. A lot of water go through them in a day, week, month, and year, and a lot of impurities entrained in that water goes through them at the same time. It is imperative that those impurities not be deposited within the entrails of the boiler, impairing or ruining altogether its future operation. In practice, boilers are extremely susceptible to scaling (another word for solid deposition) from calcium, magnesium, carbonate, chloride, sulfate, phosphate, and other ion species present in feedwater. As the water vaporizes in a boiler, the concentration of impurities in the water rises until the saturation limit of those scaling impurities is exceeded. When this occurs, such concentrated ions very rapidly form impervious scale (which has the consistency of sandstone or shale and often looks like plaster of Paris) that lines and plugs boiler plates, pipes and tubes that carry the water. Scale (typically calcium carbonate, calcium sulfate, and magnesium sulfate) is a non-conducting material that deposits on the surface of the interior pipes and surfaces. On boiler plates, it reduces the efficiency of heat transfer to form steam. In pipes and tubes, the scale grows from the walls to the center continuously constricting the flow of water. The process is not unlike cholesterol depositing in a human artery and plugging it. The offending ions form compounds that precipitate inside pipes just like cholesterol precipitates inside blood vessels and impedes blood flow. Like cholesterol deposition, scaling in boilers is far from a trivial problem. Scaling can ruin a boiler forever, rendering it useless and exposing it to full, complete, and immediate replacement. Scaling shuts down and ruins boilers, and shutdown of boilers shuts down entire electric generation or industrial processing plants. Scaling is one of the leading causes for energy losses in steam generation—reduced heat transfer from the heating units to the water and increased pumping costs. Boilers simply cannot bear any risk of scaling. Boilers spend hundreds of millions of dollars to prevent scaling and ensure reliability of operation and long life. The most common practice in boiler water demineralization/deionization is to add polyphosphate water treatment chemicals that chemically bind Ca++ to retard CaCO3 scale formation on the heat exchanger surfaces and in process pipes and tubes. Polyphosphates are environmentally very dangerous and very degrading and simply cannot be released to the environment. These are the same chemicals that were restricted or banned in soaps and detergents in the late 1970s. Polyphosphates cause explosive algae growth, which sucks the oxygen out of ponds and kills indigenous aquatic life. In practice, addition of polyphosphates to boiler feedwaters entails adding very large quantities of environmentally hazardous chemicals to large quantities of working boiler water. After the addition of these polyphosphates, discharge of the resulting water to the environment is absolutely not allowed—period. Not only does polyphosphate addition represent a serious threat to the aquatic environment in the event of discharge, polyphosphate pretreatment imposes a high operating and maintenance cost on the boilers themselves. Polyphosphates are not at all inexpensive. Furthermore, polyphosphate addition is at its very core highly inefficient. Polyphosphates do not remove or precipitate the pernicious calcium, magnesium, carbonate, sulfate, and other ions. Polyphosphates merely retard their rate of deposition so that they make it all the way through the boiler before they scale. Scale still forms, only at a slower rate. As such, polyphosphate treatment has a low efficiency. Boiler equipment still degrades and depreciates and deteriorates. Polyphosphates are themselves in a very important sense "Rube Goldberg contraptions", binding dissolved ions for a brief period of time and getting at least some use of polluted boiler feedwater, but they pollute the wastewater in the process. Boiler water deionization using Reticle Carbon CDI is simple and direct and does not require the substitution of one pernicious chemical for another. Reticle Carbon lined electrochemical cells remove ALL ions from the feedwater, offending ions that cause scaling and nonoffending ions alike. By removing the pernicious ions, Reticle Carbon does not merely retard the rate of scaling as polyphosphate treatment does, it eliminates scaling as a possibility altogether. (There are no ions left in the water to scale!) In contrast to polyphosphate pretreatment, Reticle Carbon removes the pernicious ions altogether from the water stream. There is NO subsequent scale deposition because there are no offending ions in the boiler feedwater to deposit and scale the pipes. Deionization using Reticle Carbon CDI generally requires only one stage of Reticle capacitive deionization. Redundant Reticle units will ensure continuous operation of the boiler (one fills as the other is regenerated.) |
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copyright reticle 2003 webdesign beatriz alentejano |
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