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Comparison of the Deoxidization Efficiency of Nine Types of Boiler Deoxidizers Abstract: Analysis of the differences in deoxidization performance among 9 commonly used boiler deoxidizers, along with relevant precautions regarding the use of these deoxidizers. Keywords: Deoxidizer； Boiler deaeration ； deaerator ； Deoxygenation effect ； Oxygen content in feedwater I. Hazards of oxygen corrosion in boilers Oxygen dissolved in water is the main factor causing corrosion in boilers. Deoxygenation of boiler feedwater involves removing oxygen and other gases from it, thereby preventing oxygen corrosion in the boilers and their associated equipment and pipelines, and ensuring the safe and stable operation of the boilers. Oxygen corrosion is one of the main issues affecting the safe operation and service life of boilers. The deaerator is one of the key devices in boilers and heating systems; if its deoxygenation efficiency is low, it will cause severe corrosion to the boiler feedwater pipes, economizers, superheaters, and other auxiliary equipment in the boiler. The economic losses resulting from oxygen corrosion can be dozens or even hundreds of times higher than the cost of the deaerator itself. ▲The image above shows a tube explosion caused by overheating and oxygen corrosion in the superheater of a boiler at a company in Baotou. Oxidation products adhering to the walls of the superheater tubes were magnetite, Fe3O4. Different types of deaerators and operating conditions result in varying requirements for deaeration. According to the GB/T1576-2008 standard \"Water Quality for Industrial Boilers\", steam boilers with an hourly evaporation capacity of 2 tons or more, as well as hot water boilers with a water temperature of 95°C or higher, must be deaerated. Additionally, depending on the operating pressure of the boiler, it is necessary to keep the dissolved oxygen level in the feedwater within acceptable limits. For example, the oxygen content in the feed water of atmospheric deaerators should be less than 15 mg/L, while that in the feed water of pressure deaerators should be less than 7 mg/L. The dissolved oxygen level in the water used for flushing deaerators should be below 5 ppb. II. Comparison of the deoxygenation efficiency of 9 common boiler deoxidizers In the actual operating conditions of boiler users, various problems and abnormalities often occur during the operation of deoxidizers. For example, high deaerator water level, low deaerator water level, increased deaerator pressure, vibration in the deaerator itself and its connected pipes, high dissolved oxygen level in the water leaving the deaerator >7ppb, overpressure in the deaerator, low deaeration efficiency, and excessive dissolved oxygen in the water, among others ； It also often experiences deaerator failures that lead to shutdown ； The deaerator is not put into operation due to mismatch with actual operating conditions ； The deaerator experiences large temperature fluctuations, resulting in low deoxygenation efficiency ； Factors such as low management levels of deaerator equipment lead to oxygen corrosion of the boiler itself, as well as of the equipment and pipelines in the steam and condensate systems. This results in a red color in the boiler water, red-colored steam and condensate, excessive iron content in the condensate, formation of iron oxide scale within the boiler system along with corrosion beneath that scale. As a consequence, the boiler’s output decreases, the flue gas temperature rises, and fuel resources are wasted. If the boiler continues to operate under conditions of oxygen corrosion for an extended period or if the issue is not properly addressed, it can lead to more severe boiler failures, causing shutdowns of the unit, damage to equipment, and even safety incidents. ▲The image above shows oxygen corrosion in a 25-ton steam boiler at a mine in Inner Mongolia; the iron content in the boiler water was above the permissible level, and the color of the boiler water was red. When there are problems with the boiler’s deaeration equipment, deoxidizers are usually used as a substitute. Today, we will focus on comparing the effectiveness of 8 commonly used boiler deoxidizers. Comparison of the deoxygenation efficiency of different boiler deoxygenizers 1. Sodium sulfite Na2SO3 deoxygenizer: Sodium sulfite is generally used as an auxiliary for thermal deoxygenation; the reaction equation between sodium sulfite and oxygen is: 2Na2SO3 + O2 → 2Na2SO4. Advantages of sodium sulfite deoxidizer: It can remove oxygen at room temperature ； Low cost and simple to operate. Disadvantages of sodium sulfite for deoxygenation: The dosage and frequency of addition need to be carefully controlled, as it is difficult to manage, and the deoxygenation effect is unstable ； The salt content in the water in the boiler increases, which leads to higher wastewater discharge and greater heat loss ； Since sodium sulfite decomposes under high temperatures in the boiler to produce harmful gases that cause metal corrosion, it is only suitable for medium and low-pressure boilers, and cannot be used in high-pressure boilers ； It is generally used in small boiler rooms and thermal systems with high requirements for water quality as an auxiliary deoxygenation method, and it is not suitable for many applications where water quality is a concern ； Sodium sulfite is a strong reducing agent; it should be stored and used to prepare sodium sulfite solutions in sealed containers that are free from contact with air, in order to prevent it from oxidizing and becoming ineffective. In practice, cases of sodium sulfite losing its effectiveness due to oxidation are quite common. Don’t laugh – the author has encountered several customers who continued to use sodium sulfite that had already become ineffective for oxygen removal purposes. ▲The image above shows oxygen corrosion of a boiler in a heating company in Shaanxi, with the boiler water appearing red in color ； Oxygen corrosion and weakly acidic corrosion in steam condensate systems; yellowing of steam condensate water due to excessive iron content; comparison of the deoxidization efficiency of different boiler deoxidizers. 2. Hydrazine N2H4 as a deoxidizer – hydrazine-based deoxidizing agents. Hydrazine is a very strong reducing agent in alkaline aqueous solutions; it can reduce the dissolved oxygen in water, with the reaction equation being: N2H4 + O2 → N2 + 2H2O. Advantages of hydrazine for oxygen removal: Hydrazine does not increase the salt content in boiler water; the reaction produces nitrogen and water, which helps to prevent further corrosion of the boiler. Disadvantages of hydrazine for oxygen removal: Hydrazine is a suspected carcinogen; it is volatile, toxic, and flammable. Safety precautions must be taken when using it, and it should not be used in domestic boilers ； The excess amount of hydrazine should be appropriate; too much excess may carry unreacted hydrazine into the water vapor. Comparison of the deoxygenation efficiency of boiler deoxygenizers: 3. Propyl oxime, C3H7NO – a deoxygenizing agent. Propyl oxime as a deoxygenizer. Propanethioxime, abbreviated as DMKO or also known as dimethylthioxime, possesses strong reducing properties and readily reacts with oxygen in the feed water, thereby reducing the dissolved oxygen level in it ； Non-toxic, an ideal product for replacing traditional chemical deoxidizers such as hydrazine in feedwater for medium and high-pressure boilers. When in use, control the excess amount of propyl oxime in the feed water at 15–40 μg/L. Advantages of propyl oxime for deoxygenation: non-toxic and causes no environmental pollution ； Propionoxime undergoes passivation reactions with metals, and can be used as a passivator after boiler pickling. Disadvantages of propionoxime for oxygen removal: It is a new type of oxygen remover, and more experience and better methods are needed to utilize it effectively ； There have been cases where, after individual users used dimethyl oxime, the boiler’s heat-exchanging surfaces corroded and led to tube failures ； The price of propionoxime is not low. Comparison of the deoxygenation efficiency of boiler deoxygenizers 4. Carbohydrazide CON4H6 deoxygenizer – Carbohydrazide as a deoxygenizing agent. Carbonylhydrazide, also known as diaminourea or carbazide, has the molecular formula CON4H6. It is a derivative of dinitrogen; it is superior to hydrazine in terms of deoxygenation capabilities and metal purification. In the field of water treatment, carbonylhydrazide can be used as a deoxygenating agent for boiler water, as well as a passivating agent for metal surfaces to reduce the rate of metal corrosion. Carbazide can react with dissolved oxygen in water to produce carbon dioxide, nitrogen, and water. The reaction between carbazide and oxygen is as follows: CON4H6 + 2O2 = 2N2 + 3H2O + CO2. The advantages of using carbazide for oxygen removal include its low toxicity, high melting point, and safe and environmentally friendly usage. Disadvantages of carbazide deoxygenation: It is generally used as an auxiliary method for thermal deoxygenation, and carbazide is expensive. ▲The image above shows oxygen corrosion of a boiler in a company in Shandong; iron oxide scale is attached to the boiler tubes. Comparison of the efficiency of different boiler deoxidizers. 5. Acetaldoxime C2H5NO – a deoxidizer of this type. The molecular formula of acetaldoxime is C2H5NO. It is a reducing agent with low toxicity, and it replaced the highly toxic hydrazine as a deoxidizer for boiler water quite early on. Acetaldoxime’s deoxidization efficiency is 40 times that of hydrazine; therefore, it is widely used as a new type of deoxidizer in thermal power plants across the country. By adding acetaldoxime to the unit using makeup water treated with chemicals, an excellent deoxygenation effect can be achieved. Especially when demineralized water is directly used as makeup water for the condenser, taking advantage of acetaldoxime’s ability to remove oxygen at low temperatures and at a rapid pace, most of the oxygen can be removed in the condenser, thereby reducing corrosion in the high-pressure heaters and their pipelines. Advantages of acetaldoxime for oxygen removal: It can remove oxygen at low temperatures, and the oxygen removal rate is fast ； Low toxicity. Disadvantage of acetaldoxime deoxygenation: The vapor mixed with air can be explosive ； Flammable hazard characteristic: easily ignitable; releases toxic nitrogen oxide gases when heated intensely ； Store away from sources of fire and heat; the storage temperature should not exceed 30°C, and it is expensive. Comparison of the deoxidization efficiency of boiler deoxidizers 6. Ascorbyl C6H806 deoxidizer: Ascorbyl and its sodium salt deoxidizers. Isascorbic acid and its sodium salts are low-volatility deoxidizers; they are isomers of vitamin C (L-ascorbic acid). Their reaction with dissolved oxygen is complex, as it involves several intermediate steps to proceed, and the mechanism behind this process is not yet fully understood. Due to their safety, they are widely used as deoxidizers in food and feed applications. In our country, some manufacturers also use it as a deaerator for boiler water. Ascorbyl acid and its sodium salts are superior to hydrazine in terms of reducing iron ion levels and slowing down corrosion in the feedwater system; moreover, their final decomposition products are CO2, so they do not cause organic acid corrosion in the low-pressure cylinders of steam turbines. Advantages of ascorbyl acid and its sodium salts for deoxygenation: fast deoxygenation speed ； Non-toxic and safe. Disadvantages of ascorbyl acid and its sodium salts in oxygen removal: the need to control microbial growth in their dilute solutions ； Sodium erythorbate decomposes at high temperatures, producing corrosive dissolved solids; at 300°C, the decomposition products consist of 71.07% lactic acid, 20.48% acetate, and 8.44% formate, and the sodium salts affect the conductivity of water and steam ； It can only remove oxygen without providing passivation. ▲The image above shows oxygen corrosion in a boiler belonging to a company in Shandong; corrosion pits have formed due to corrosion beneath the iron oxide scale on the boiler tubes. Comparison of the efficiency of different deoxidizing agents used in boilers. 7. Deoxidization using steel scrap. Steel scrap deoxidation also falls under chemical deoxidation; as water flows through the steel scrap filter, the steel scrap is oxidized, thereby removing the dissolved oxygen from the water. This method comes in two types: standalone and attached. When using steel scrap, it needs to be compressed tightly – the tighter, the better. The higher the oxygen content in the water, the lower the flow rate required. It is generally used in small boiler rooms where high requirements are not placed on the quality of the feed water, or as make-up water for heating networks, as well as for additional deoxidization after thermal deoxidization in high-pressure boilers; it is usually used only as an auxiliary measure. Advantages of steel scrap for oxygen removal: long service life, no environmental pollution, and the oxygen content in the water remains below 0.05 mg/L, meeting the water quality requirements for low-pressure boilers ； Operates at room temperature, no heating required; low operating costs ； The amount used is small; generally, the consumption of deoxidizer is 10 g per ton of water. Disadvantages of steel scrap degassing: The water temperature for steel scrap degassing needs to be above 70°C, with temperatures of 80–90°C yielding the best results; the degassing effect is poorest at temperatures of 20–30°C ； Because since the introduction of steel scrap for deoxidation, there have been few technological improvements, and the deoxidation effect is not very reliable. Comparison of the deoxygenation efficiency of boiler deoxygenizers 8. The anti-corrosion and scale-removal capabilities of multi-functional BF as a substitute for deoxygenizers – its anti-corrosion effects. The anti-corrosion and scale-removal capabilities of multi-functional BF as a substitute for deoxygenizers. The multi-functional BF anti-corrosion and descaling agent is a patented product of Beijing University of Chemical Technology, and it represents the core technology in the Innovation Fund project of the Ministry of Science and Technology titled “Near-zero waste steam generation technology”. This product passed the “Registration by the China Boiler Water Treatment Association” program in 2003. The multi-functional BF anti-corrosion and scale-removal agent does not use traditional deoxygenation methods that involve chemical reactions with oxygen; instead, it creates a protective film on the metal surfaces of boiler systems. This film functions similarly to a passivation layer, preventing oxygen molecules from corroding the metal surfaces of boiler equipment, thereby avoiding corrosion in the boiler system and protecting its equipment and pipelines. As a result, it offers better anti-corrosion effects compared to traditional deoxygenators. Advantages of the multi-functional BF anti-corrosion and scale-removal agent: 1. Provides anti-corrosion protection by forming a protective film; corrosion inhibition rate ≥99%, scale inhibition rate ≥99%; wide range of scale inhibition effectiveness; phosphorus-free formula that serves as a substitute for trisodium phosphate ； 2. As a boiler shutdown protection agent, it provides a corrosion inhibition rate of ≥99% for the protection of boilers and related system equipment during shutdowns. It is sufficient to simply seal the boiler equipment when it is shut down, eliminating the need for frequent regular inspections. There is no need to drain the boiler water either when starting up or shutting down the boiler. It is suitable for use in situations involving long-term shutdowns, frequent start-ups and shutdowns, as well as prolonged intermittent operation of the boiler ； 3. As a scale dispersant for rust removal and dispersing iron scale ； Especially suitable for boilers in which high-temperature steam condensate is reused directly without iron removal treatment ； 4. Alkaline agents, used as pH regulators to raise the pH of feedwater and boiler water, to neutralize the weakly acidic corrosion caused by CO2, and as alternatives to sodium carbonate, sodium hydroxide, and ammonia ； 5. Scale dissolution and removal, chelation for the elimination of old scale; it replaces boiler acid cleaning maintenance, enabling damage-free online cleaning of the boiler so that it can continue to operate without needing to be shut down ； 6. Acting as an antifoaming agent to increase steam dryness and ensure steam quality ； 7. Raw water + multi-functional BF corrosion and scale inhibitor; hot water boilers can be used instead of softened water, with oxygen removal procedures to protect the environment ； 8. Raw water + multi-functional BF corrosion and scale inhibitor + multi-functional BF condensate iron removal and corrosion inhibitor, to replace the softening unit in steam boiler systems + deaeration equipment + iron removal equipment ； 9. Simple operation: Add the chemical to the make-up water tank; a pH value of 10.5–12 for the water in the boiler is considered acceptable ； 10. The chelating, dispersing, and lattice-distorting effects on scale are all non-stoichiometric and exhibit a threshold effect; a low dosage of the additive is sufficient to reduce the boiler blowdown rate. ▲The image above shows oxygen corrosion in a boiler belonging to a company in Shandong; corrosion pits formed beneath the iron oxide scale on the boiler tubes led to perforations, leaks, and tube failures. Can you see those corrosion pits that caused the perforations? Comparison of the deoxygenation efficiency of boiler deoxidizers 9. The multi-functional BF condensate iron removal and corrosion inhibitor serves as a substitute for the deoxidizer in terms of corrosion protection for steam boilers; the multi-functional BF condensate iron removal and corrosion inhibitor can fully replace the deoxidizer’s function in providing corrosion protection. The multi-functional BF condensate iron-removing and corrosion-inhibiting agent is a patented product of Beijing University of Chemical Technology, and it represents the core technology in the Science and Technology Ministry’s innovation fund project titled “Zero-waste steam generation technology”. This product passed the “Registration by the China Boiler Water Treatment Association” program in 2003. The multi-functional BF condensate iron removal and corrosion inhibitor belongs to the category of chemicals added inside the boiler. It is not a traditional deoxygenation method that involves chemical reactions with oxygen; instead, it uses a membrane to isolate oxygen and carbon dioxide, thereby preventing oxygen-induced corrosion and mild acidic corrosion in the boiler system. This helps to protect the equipment and pipelines in the boiler system. It also prevents oxygen-induced corrosion and mild acidic corrosion in the equipment and networks of both the steam system and the condensate system, offering better corrosion protection compared to traditional deoxygenators. The multi-functional BF condensate iron removal and corrosion inhibitor for steam boilers completely replaces the anti-corrosion functions of deaerators, offering 7 advantages: 1. The main components of this multi-functional BF condensate iron removal and corrosion inhibitor are neutralizers, film-forming agents, and other additives; it possesses film-forming and neutralizing capabilities, good stability, as well as an optimal vapor-liquid phase distribution ratio, enabling rapid control of corrosion throughout the entire steam boiler system. The neutralizer serves to raise the pH of boiler feedwater, furnace water, steam, and condensate, thereby preventing corrosion caused by the weak acids formed by carbon dioxide in the water ； The film-forming agent creates a hydrophobic protective film in the form of a monolayer on the metal surface; the gaps between the molecules in this film are smaller than the cross-sections of carbon dioxide and oxygen molecules, which prevents corrosion-causing gas molecules such as O2 and CO2 from coming into contact with the metal, thus avoiding corrosion of the metal ； A reasonable vapor-liquid phase distribution ratio can effectively distribute the treatment agent between the vapor and liquid phases in metal pipes, thereby effectively addressing metal corrosion in systems with both vapor and liquid phases; it is particularly suitable for the protection and anti-corrosion of equipment that uses steam intermittently. 2. The multi-functional BF condensate iron-removing and corrosion-inhibiting agent is a volatile alkaline substance. When added to the feed water and sent into the boiler, it volatilizes upon heating and enters the steam system as steam. After passing through heat exchangers or heat-using equipment, as the temperature and pressure drop, the agent dissolves back into the steam condensate for reuse in the boiler. Within the water-steam-water cycle of the boiler system, this agent forms a protective layer over the entire steam system, including heat exchangers and heat-using equipment, thereby effectively addressing the common problems of oxygen corrosion and weak acid corrosion in steam condensate. This corrosion-inhibiting mechanism not only helps to bring the iron content in the condensate within acceptable levels but also provides thorough protection for all equipment and pipelines in the boiler system, **extending the service life of the equipment. 3. The multi-functional BF condensate iron-removing and corrosion-inhibiting agent is an upgraded replacement for ammonia water; it features a reasonable vapor-liquid phase distribution ratio, good stability, and eliminates both oxygen corrosion and weak-acid corrosion in the entire system ； Adding ammonia can increase the pH value of boiler water and steam, thereby addressing weakly acidic corrosion. However, ammonia is volatile, with more in the gas phase and less in the liquid phase; it requires large quantities to be used, and it cannot prevent oxygen corrosion. The storage and use of liquid ammonia pose a hazard. 4. The multi-functional BF condensate iron removal and corrosion inhibitor requires simple operating conditions in practical use; there are no requirements regarding the condensate temperature or the level of iron in the condensate. However, some iron removal filtration devices do have requirements for the condensate temperature and iron content. The multi-functional BF condensate iron-removing and corrosion-inhibiting agent exhibits excellent buffering capacity despite fluctuations in production load; it requires no precise dosing, and thus does not affect the performance parameters of water treatment. 5. The film-coating process is fast, and the iron ion level (total iron) in the condensate water meets the specified standards within 72 hours, facilitating drug testing experiments. It can completely replace deaerators and deoxidizers. 6. The multi-functional BF condensate iron removal and corrosion inhibitor requires a low dosage; as its accumulation in the system increases, both the cost and the amount of wastewater generated from backwashing are reduced. There are no issues related to wastewater discharge associated with backwashing, as is the case with other high-temperature condensate iron removal filtration systems. 7. Compared with common high-temperature steam condensate iron removal devices on the market, the multi-functional BF condensate iron removal and corrosion inhibitor requires no substantial investment in fixed equipment, nor does it entail costly filter media replacements (with a service life of around 3 years and total costs accounting for 20–30% of the initial investment). It not only protects the system’s equipment and pipelines and extends the service life of the boiler system but also completely eliminates the source of iron ions, enabling the safe reuse of condensate in boilers and thus providing a thorough solution to the problem of iron in condensate. Colleagues and classmates, aside from these eight common boiler deoxidizers, are there any other boiler deoxidizers that you are aware of? How did your company address oxygen corrosion in its boilers? Regarding issues such as oxygen corrosion in boilers, boiler deoxidizers, the effectiveness of boiler deoxidization, the oxygen content in boiler feedwater, corrosion and scaling in condensers, red-colored wastewater from boiler feedwater, corrosion, scaling, and tube failures in boilers or superheaters, corrosion in steam systems, excessive iron levels in steam condensate, yellowish or red-colored steam condensate, as well as online cleaning and descaling technologies that allow for the removal of scale from condensers without shutting down the system, and online descaling technologies for boilers without interrupting operations, Yan Hui from Beijing University of Chemical Technology at I86OO475З86 is always available to discuss these issues, exchange experiences and insights, and to share knowledge regarding the management and use of boiler equipment, so as to help resolve various practical problems related to boilers. Comparison of the deoxygenation efficiency of nine types of boiler deoxygenators. III. Case study of how the multi-functional BF anti-corrosion and scale-removal agent can fully replace the functions of a deoxygenator in terms of anti-corrosion performance. Report on the experiment conducted to address corrosion in the boiler system of Shanxi XX Company and the reddening of boiler water, through the online addition of chemicals. 1. Overview: Shanxi XX Company has two newly installed 6t/h natural gas steam boilers, one in use and one as a backup. The feed water is resin-softened water, and there is no deoxygenator in use. Currently, the new production line is in the commissioning phase. Two boilers are used alternately to provide heating on a intermittent basis, with heating operating for an average of 9 hours per day and the boilers being shut down for 15 hours. The steam condensate is not reused in the boilers, and no scale inhibitors, corrosion inhibitors, or anti-corrosion agents are added to them. Due to the lack of deaeration in the boiler’s thermal system, as well as the special operating conditions involving intermittent heating with shutdowns lasting over 15 hours per day, the water in the two boilers has been red-colored for more than 6 months; corrosion inside the boilers is severe, and the amount of waste water discharged from the boilers is high. ▲The image above shows oxygen corrosion in a boiler at a company in Shanxi. A large amount of reddish-brown boiler wastewater is discharged into the gutters, and the red color of this water is caused by excessive levels of iron ions in it. The main cause of these high levels of iron ions is oxygen corrosion. The oxygen corrosion in this boiler is quite severe; oxide scale has formed on the boiler’s heating surfaces, along with corrosion beneath that scale. Increasing the amount of wastewater discharged does not solve the problem. ▲The image above shows a boiler in a company in Shanxi that is suffering from severe oxygen corrosion; the color of the boiler water is red, and the amount of waste water discharged from the boiler is high. In order to address the corrosion in the boiler system, extend the service life of the boiler equipment, remove the iron oxide scale attached to the boiler’s heating surfaces, reduce the amount of waste water discharged, improve the efficiency of the boiler, lower operating costs, and ensure the safe operation of the boiler equipment, it is necessary to carry out cleaning and anti-corrosion treatment tests on the boiler system without shutting it down. 2. The test involved using a multi-functional BF anti-corrosion and scale-removal chemical added to the boiler water to carry out pre-coating treatment on the feedwater pipes and the boiler without shutting down the boiler. This treatment chelated and removed the iron oxide scale attached to the heating surfaces of the boiler, thereby addressing the issue of corrosion in the boiler system at its source, extending the service life of the boiler equipment, and ensuring production safety. At the same time, ensure that the water quality of the boiler remains stable over the long term and meets national standards. Test and analyze the pH value, total alkalinity, and iron ion concentration of the boiler water to determine an appropriate dosage of protective chemicals. Improve boiler water quality, increase the concentration ratio, reduce boiler blowdown volume, and enhance the utilization efficiency of thermal energy. 3. Test process: 1. In this trial, the BF anti-corrosion and scale-removal agent was added to the boiler feed water to carry out an online anti-corrosion treatment without shutting down the boiler. Given that the boiler produces a low amount of gas (an average of 40 tons per day), the replacement of water in the boiler is slow, there is a large amount of iron oxide corrosion deposits inside the boiler, and waste discharge is insufficient, it was estimated that the trial period for this online anti-corrosion treatment would be 30 days. The dosage of the agent was increased at first and then decreased gradually, depending on the extent of scale removal and film formation in the boiler; samples were taken after each adjustment to the agent concentration to analyze parameters such as the iron ion concentration, pH value, and total alkalinity in the boiler water. 2. Preparation of test materials 3. Training for boiler operators ▲The image above shows severe oxygen corrosion in the boiler of a company in Shanxi; the color of the boiler water was red. On the morning of July 18, 2023, at 8 o’clock, an experiment was initiated to treat this issue by adding chemicals online, without shutting down the boiler, due to corrosion in the boiler system and red-colored boiler water at Shanxi XX Company. Water sampling from the boiler (see figure above) was carried out; after sampling, the boiler began to discharge waste water. Following this, BF anti-corrosion and scale-removal agent was added to the soft water tank to conduct treatment tests. Due to severe corrosion in the boiler system, slow water circulation within the system, and the fact that it was the first time such treatment was applied, a higher dosage of the chemical was used. ▲The image above shows a boiler in a company in Shanxi that is suffering from severe oxygen corrosion; the boiler water has turned red. After applying chemicals for treatment, a sample of the boiler water was taken at 8 a.m. on July 19 (as shown in the image). After sampling, the boiler began to discharge waste water, and after that chemicals were added again. The frequency of waste water discharge was increased as well as the amount of waste water discharged, in order to accelerate the replacement of the boiler water. ▲The image above shows severe oxygen corrosion in the boiler of a company in Shanxi. Two days after treatment with chemicals, a water sample from the boiler was taken at 8 a.m. on July 20. After those two days of treatment, the chelating descaling effect of the BF anti-corrosion descaler became apparent; the iron oxide deposits inside the boiler were chelated, resulting in a significant increase in the turbidity of the boiler water as well as an increase in the concentration of iron ions. A sample of the boiler water was taken (as shown in the image above). After taking the sample, the boiler began to discharge waste water. Once the discharging process started, more chemicals were added, and the frequency of discharging increased to accelerate the replacement of the water in the boiler. ▲The image above shows severe oxygen corrosion in the boiler of a company in Shanxi, resulting in red-colored boiler water. Online chemical treatment was carried out without shutting down the boiler. Boiler water samples were taken from 7 Month 21 st to 8 Month 16 th at 8 a.m. During this period, the boiler was not in operation for a few days, and no samples were taken during those times. The turbidity of the boiler water fluctuated several times as the iron oxide corrosion products inside the boiler were chelated away (as shown in the image above). The dosage of the BF anti-corrosion and scale-removal agent, as well as the amount of boiler water drained, were reduced accordingly as the turbidity of the water decreased, until normal conditions were restored. On the morning of August 17, the tests were halted; water samples from the boiler were taken and sent to a third-party testing laboratory, where it was confirmed that they met the required standards. After 31 days, the corrosion in the boiler system of Shanxi XX Company, as well as the reddening of the boiler water, were successfully addressed through the online addition of chemicals without having to shut down the boiler. IV. Case Study of the Complete Replacement of Deaerator Anticorrosion Agents by Multi-Function BF Condensate Iron Removal and Corrosion Inhibition Agent in Steam Boilers: In May 2022, a 25-ton steam boiler at XX Company in Hebei was operating at low load as part of a new factory and production line; the deaerator was not in use. Oxygen corrosion and weak acid corrosion were severe in the steam system, and the iron content in the steam condensate was above acceptable levels. The condensate was red in color. The high-temperature steam condensate was discharged into sewers instead of being reused in the boiler, which not only wasted water and energy but also polluted the environment by increasing emissions. A test report on the use of multi-function BF condensate iron removal and corrosion inhibition agent to address these issues was prepared for the boiler feedwater. Due to space constraints, more case reports are omitted. Students who are interested are welcome to contact Yan Hui at any time to obtain the reports and engage in technical discussions. Comparison of the deoxidation efficiency of nine types of boiler deoxidizers (Yan Hui)