Solution to the corrosion of the steam generator boiler, red sewage color, and excessive condensate iron

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The steam generator boiler is corroded, the sewage is red in color, and the condensate iron exceeds the standard. The steam generator is also called a steam heat source machine, and it is also a boiler with high thermal efficiency. The steam generator has high thermal efficiency, no pollution, low emissions, and a compact structure. Because the water volume of the steam generator is less than 30L, it is not a special equipment within the scope of supervision. There is no need to report for inspection, and there is no need for a professional boiler to be on duty. It saves complicated procedures and reduces production costs. It is favored by the majority of users. In recent years, steam generator equipment has been widely used in many fields such as food processing, medical pharmaceuticals, biochemical industry, wine distillation, washing and ironing, textile dyeing and finishing. ▲Corrosion of the steam generator cross-flow pipe in the washing plant, redness of the sewage, white linen washed with condensate, redness of bed sheets and clothing 1. Six common problems caused by water quality in steam generators. Although steam generators have many advantages, it is not uncommon for water quality problems to cause steam generator failures and problems. Poor user experience of steam generators is caused by 6 common problems caused by water quality.: 1. One of the six common problems caused by water quality in steam generators - scaling shortens the service life of steam generators. The water quality in different regions is different. In some areas, the water quality is hard and the content of salt substances in the water is high, that is, the content of calcium salts and magnesium salts is high. The one with more content has greater hardness, and vice versa (the softness and hardness of water is calculated based on the concentration of calcium and magnesium ions in the water). Although pure water purifiers, resin softened water, RO reverse osmosis desalted water or desalted water are used, the use and management level of related water treatment equipment fluctuates. After long-term use, scale will form in the steam generator, the through-flow pipe will be blocked, and even water leakage and overheating will cause the pipe to burst, making the steam generator unusable. 2. The second of the six common problems caused by water quality in steam generators - affecting steam quality and poor steam cleanliness. Improper management of water treatment agents such as sodium hydroxide and trisodium phosphate in the steam generator pot water causes the steam generator pot water to be too alkaline, which will produce a large amount of foam and azeotrope of steam and water, causing the steam dryness to decrease and worsening the steam quality. The steam will carry the salt of the boiler water and form salt scale. It is easy to produce salt accumulation or even blockage in the superheater. ； If the relative alkalinity of the boiler water, that is, the free alkalinity NaOH, is too high, the protective film on the metal surface of the steam generator through-flow tube will be destroyed due to dissolution, and it is easy for the metal to undergo alkaline corrosion at riveting and expansion tubes, resulting in caustic embrittlement, that is, alkali embrittlement. 3. The third of the six common problems caused by water quality in steam generators - corrosion of steam generator tubes. The water supplied to the steam generator is not deoxidized and is acidic. Under the combined action of oxygen corrosion and weak acid corrosion caused by carbon dioxide, the steam generator tubes will form iron oxide scale and corrosion under the scale. The iron oxide scale and corrosion under the scale will continue. As the corrosion pit deepens, the final result will inevitably be perforation and leakage of the steam generator tube. 4. The fourth of the six common problems caused by water quality in steam generators - corrosion of the steam system of the steam generator, and excessive iron content in the condensate water. Usually the steam and condensate water in the steam generator are relatively pure, have poor buffering properties, and have a low pH value and are acidic. They are prone to oxygen corrosion and weak acid corrosion caused by carbon dioxide. The final product of corrosion, iron ions, dissolves in the condensate water, causing the color of the iron in the condensate water to turn yellow or red. The iron content in the condensate water exceeds the standard, resulting in high-temperature and pure steam condensate water that cannot be directly recycled. 5. Five of the six common problems caused by water quality in steam generators - the steam generator boiler water is red, and the drainage water is red. The steam generator has too many iron ions in the boiler water due to corrosion, or the high-temperature steam condensate with excessive iron ions is directly reused in the steam generator without treatment, resulting in an increase in iron ions in the steam generator boiler water. As the boiler water evaporates and concentrates, the colorless ferrous iron ions are oxidized into ferric iron. The steam generator will appear red, the drainage water will be red, or the iron oxide scale will form and corrode under the scale. 6. The sixth of the six common problems caused by water quality in steam generators - increased cleaning costs. There is more and more scale in the steam generator through-flow tubes, the thermal conductivity decreases, the efficiency of the steam generator decreases and the output is poor, requiring more and more additional energy to be consumed, which virtually increases the operating cost of the steam generator. If you need to clean the scale in the through-flow pipe, shut down the furnace for pickling, replace the liner, etc., it will not only increase the operating cost, but also delay normal production. ▲Corrosion of the steam generator cross-flow pipe of XXX Washing Plant in Wujiang, Jiangsu Province, the color of sewage turns red, the white linen and sheets washed with condensed water turn dark and red. 2. The steam generator boiler corrodes, the color of sewage turns red, and the condensate iron exceeds the standard. Solutions: Laundries, washing plants, and the textile printing and dyeing industry are the industries that use the most energy in the country. * * Focus on industries that implement supervision on energy conservation and environmental protection. Jiangsu Wujiang XXX Washing Factory is adapted to * * Energy saving and emission reduction policy, three new 1-ton low-nitrogen steam generators were installed, running 12 hours a day, with a gas production of 24 tons, and the steam pressure was set to 4kg-6kg (0.4-0.6MPa). RO reverse osmosis desalted water was used as supplementary water. The high-temperature steam condensed water was not reused in the desalted water tank but used for washing. The sewage was discharged once a day after get off work. After the steam generator pot of the washing plant was in operation for about 7 months, the master of the pipe equipment in the laundry room of the washing plant discovered that the water in the steam generator boiler was red and the sewage was red in color (right picture below). Increasing the sewage discharge could not solve the problem. ； The appearance of high-temperature steam condensation water is relatively pure and transparent (left in the picture below). The color of white linens and bed sheets washed with high-temperature steam condensation water will appear dark and red. ▲The through-flow pipe of the steam generator in the laundry room of the washing plant is corroded, and the drainage water is red (right). The appearance of the steam condensate is relatively pure and transparent (left). The white linen and bed sheets washed with condensed water are dark and red in color. Dear colleagues, if you encounter this situation, the steam generator boiler water is red, the drainage water is red in color, and the white linen and bed sheets washed with high-temperature steam condensate are dark and red in color. What will you do? Regarding the corrosion of the steam generator boiler, the red color of the steam generator discharge water, the pH value of the boiler feed water, the redness of the boiler water, the hardness of the return water, the boiler corrosion and scale bursting, the corrosion of the steam system, the iron content of the steam condensate water exceeding the standard, the color of the steam condensate turning yellow, boiler scaling, online descaling technology that does not stop the boiler, and boiler water quality treatment testing. Regarding the topic, Yan Hui l86OO475З86, Beijing University of Chemical Technology, welcomes colleagues to discuss issues and exchange experiences. Colleagues are always welcome to communicate new technology information related to steam generators. Colleagues are always welcome to share their experience in the management and use of steam generator boiler equipment, and learn from each other on solving various practical problems of steam generators. * . The steam generator boiler is corroded, the discharge water is red in color, and the condensate iron exceeds the standard. 1. The reason for the red color of the waste water from the steam generator pot. The reason for the red color of the waste water from the steam generator pot of XXX Washing Plant in Wujiang, Jiangsu Province is: Steam generator without deaeration measures ； The replenishing water of the steam generator is desalted water treated by RO reverse osmosis. The desalted water is relatively pure and has poor buffering properties. Usually the desalted water has a low pH value and is weakly acidic. Under the joint action of oxygen corrosion and weak acid corrosion, the corrosion products of the steam generator through-flow pipe are iron ions in the boiler water. As the steam generator pot water continues to evaporate and concentrate, the colorless ferrous iron ions in the pot water are oxidized into ferric ions. The color of the steam generator pot water begins to turn yellow, red, or even black in severe cases. ▲The steam condensate water from the steam generator in the laundry room of the washing plant appears to be relatively pure and transparent, but in fact the colorless ferrous iron ions exceed the standard. After being left to stand for a long time and oxidized into colored ferric ions, the color of the condensed water begins to turn yellow. 2. The appearance of high-temperature steam condensate water is relatively pure and transparent. The reason why the white linen and bed sheets washed with condensed water are dark and red. The high-temperature steam condensate water from the steam generator of XXX Washing Plant in Wujiang, Jiangsu Province is relatively pure and transparent in appearance. The reason why the white linen and bed sheets washed with condensed water are dark and red is: High-temperature steam and condensate are purer than demineralized water and have poorer buffering properties. They are close to pure water. Usually, the pH value of untreated steam condensate is between 5.5-6.5, which is highly acidic and corrosive. The final product of corrosion of thermal equipment and pipelines such as ironing machines of steam systems or steam generators is It is the colorless ferrous iron ion left in the steam condensate water. The content of iron ions in the steam condensate water is usually less than 600 micrograms per liter. This is the reason why the appearance of the high-temperature steam condensate water from the steam generator of XXX Washing Plant in Suwujiang is relatively pure and transparent, but the iron content in the condensate water exceeds the standard. In order to save energy and water resources, XXX Laundry Factory in Wujiang, Jiangsu, washed white linens and bedsheets with high-temperature steam condensation water that contains colorless iron ions exceeding the standard. The colorless ferrous iron ions in the steam condensation water left on the linens and bedsheets are oxidized into colored ferric ions when they are dried and ironed. This is why the appearance of high-temperature steam condensation water is relatively pure and transparent, but the white linen and bedsheets washed with condensed water are dark and red. 3. The steam generator boiler is corroded, the discharge water is red in color, and the condensate water iron exceeds the standard. The solution is to solve the steam generator cross-flow pipe corrosion, the discharge water is red in color, the steam and condensate water system is corroded, and the condensate water iron exceeds the standard in the XXX washing plant in Wujiang, Jiangsu Province. It is necessary to solve the oxygen corrosion and weak acid corrosion of the steam generator cross-flow pipe and the steam and condensate water system at the same time. Since the steam generator of XXX Washing Plant in Wujiang, Jiangsu Province runs for 12 hours a day and shuts down for 12 hours, this shutdown time is too long, the gas production is small, and the intermittent heating conditions are not conducive to the process selection of anti-corrosion and corrosion inhibition measures for the steam generator. Our suggestion is to add BF-31T condensate system protective agent to the desalted water of the steam generator, and use the anti-corrosion and corrosion inhibition properties of BF-31T condensate system protective agent to completely solve the problems of steam generator boiler corrosion, red color of sewage, excessive condensate iron, and large sewage discharge. Since a small amount of chemicals remain in the high-temperature steam condensate water, the high-temperature steam condensate water will not be used for soaking and washing clothes after iron removal reaches the standard. Instead, it will be put into the desalted water tank and directly reused in the steam generator to save energy and desalted water resources. 4. BF-31T condensate system protective agent has 7 technical advantages. On the morning of January 8, 2008, Beijing University of Chemical Technology’s project "New Material Protection Technology and Chemical Phase Separation System Balance Research and Its Application in Industrial Boilers" won the * * Second Prize of Technical Invention Award. BF-31T condensate system protective agent is a core patented product of the Beijing University of Chemical Technology's award-winning new technology project - zero-emission steam generation technology. It has 7 advantages.: ①.BF-31T condensate protective agent mainly consists of neutralizer, film-forming agent and other additives. It has film-forming neutralization function, good stability, and reasonable vapor-liquid phase distribution ratio, which can quickly control the overall corrosion of the entire steam boiler system. The neutralizing agent plays the role of increasing the pH of boiler feed water, boiler water, steam and condensate, and neutralizing the weak acid corrosion caused by carbon dioxide in the water. ； The film-forming agent forms a monomolecular layer of hydrophobic protective film on the metal surface. The gaps between the film molecules are smaller than the cross-sections of carbon dioxide and oxygen molecules, preventing corrosive gas molecules O2 and CO2 from contacting the metal, thereby preventing corrosion of the metal. ； A reasonable vapor-liquid phase distribution ratio can effectively distribute the agent into the vapor-liquid phase in the metal pipeline, which can effectively solve the metal corrosion of the vapor-liquid two-phase system. It is especially suitable for the protection and anti-corrosion of intermittent steam equipment. ②.F-31T condensate protection agent is a volatile alkaline agent. The agent is added to the feed water and enters the boiler. It volatilizes when heated and enters the steam system with the steam. After the agent passes through the heat exchanger or heating equipment, as the temperature and pressure drop, the agent dissolves into the steam condensate water and is reused in the boiler. The agent will be included in the heat exchanger in the water-steam-water cycle of the boiler system. Or the steam system including the heating equipment is covered with film protection to completely solve the common oxygen corrosion and weak acid corrosion of steam condensate. This corrosion inhibition mechanism can solve problems such as excessive condensate iron, red color of condensate water, redness of furnace water, boiler iron oxide and scale corrosion. It not only makes the condensate iron meet the standard, but also completely protects the entire boiler system equipment and pipelines. * * Extended equipment service life. ③.BF-31T condensate protective agent is an upgraded replacement product for ammonia water. It has a reasonable vapor-liquid phase distribution ratio and good stability. It can completely solve the oxygen corrosion and weak acid corrosion of the overall system. ； Adding ammonia can increase the PH value of furnace water and steam, and can solve weak acid corrosion. However, ammonia is volatile, has more gas phase and less liquid phase, and uses a large amount, which cannot solve oxygen corrosion. The storage and use of liquid ammonia is a source of danger. ④.BF-31T condensate protective agent has simple requirements for on-site use. There are no requirements for condensate temperature and excess iron content in condensate water. Some iron removal and filtration equipment have requirements for condensate temperature and iron content. BF-31T condensate protective agent is not affected by production load fluctuations and has good buffering performance. It does not require precise measurement and will not affect the performance of water quality treatment indicators. ⑤.The coating speed is fast, and the condensation iron ions (full iron index) can quickly reach the standard within 72 hours, which provides convenience for drug trial experiments. It can completely replace the deaerator and deoxidizer. ⑥.BF-31T condensate protection agent is used in a small dosage. As the cumulative usage and cost of the agent in the system are reduced, there is no wastewater discharge problem like backwashing of other high-temperature condensate water iron removal and filtering equipment. ⑦Compared with the common high-temperature steam condensate iron removal equipment on the market, BF-31T condensate system protective agent does not require huge investment in fixed equipment and equipment, and does not require costly replacement of filter materials (the service life is about 3 years, the total cost is 20-30%). It not only protects the system equipment and pipelines, prolongs the service life of the boiler system, but also completely cuts off the source of iron ions, allowing the condensate water to be recycled and used safely in the boiler, achieving condensate iron removal. ▲The steam condensate water from the steam generator in the laundry room of the washing plant appears to be relatively pure and transparent, but in fact it does not develop color and the ferrous iron ions exceed the standard. ； The picture above shows the steam condensate water that reaches the iron ion standard after 72 hours of chemical treatment. It does not develop color after being left standing for a long time. The high-temperature and pure steam condensate water is returned to the desalted water tank and directly reused in the steam generator, saving energy and desalted water resources, which not only saves energy but also reduces emissions. 5. The steam generator cross-flow pipe of XXX Washing Plant in Wujiang, Jiangsu Province was corroded, the drainage water was red in color, the steam and condensate water systems were corroded, and the condensate water iron exceeded the standard. The actual working conditions of each user were different. The successful cases of previous users were not convincing, and practice is the only criterion for testing truth. In order to understand whether the BF-31T condensate system protective agent can completely solve practical problems such as the corrosion of the steam generator cross-flow pipe of the XXX washing plant in Wujiang, Jiangsu, the red color of the sewage, the corrosion of the steam and condensate systems, and the problem of excessive iron in the condensate water, we discussed with the user to conduct a trial test of the agent before formal application, and first purchased a 15-day dosage of about 5 0L, 2 barrels in total (during the overall anti-corrosion coating of the boiler system, scale removal, scale inhibition, dispersion of iron oxide scale and rust, the dosage will be gradually reduced according to the gas production firstly high and then low. In the later period, when normal, the dosage per ton of water will be around 20-50 grams, and the boiler water pH will be controlled between 10.5 and 11. If it is low, increase or decrease), and formulate a trial dosing experiment plan and specific boiler blowdown operations. After a 15-day chemical trial test, the color of the boiler water did not turn red and returned to normal, and the condensate looked pure and transparent. Based on past experience, the corrosion of the steam generator through-flow pipe, including the steam system, condensate recovery system equipment and pipelines, has been controlled. Boiler water and condensate water samples were sent to a third party for testing, and the trial treatment test of the chemical ended early. 6. Precautions In this case, the steam generator of the XXX washing plant in Wujiang, Jiangsu does not need to directly contact the materials when it is involved in production. Thermal processes such as ironing machines and dryers exchange heat through heat exchangers. The BF-31T condensate system protective agent is an organic amine preparation, which is volatile and non-toxic and can be used with confidence. In other words, BF-31T condensate system protective agent is not suitable for production conditions that require high steam quality, such as: Steaming steamed food, steaming medicinal materials, food packaging sterilization and other production processes that require steam to directly contact materials and require high steam quality. Follow Yan Hui, and next time I will introduce an example of how to solve practical problems such as boiler corrosion, boiler water redness, furnace tube burst, steam condensate water iron exceeding the standard, and large sewage discharge in the pharmaceutical industry that has high requirements for steam quality. The steam generator boiler is corroded, the sewage is red in color, and the condensate iron exceeds the standard (Yan Hui)