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Heating companies use tap water instead of softened water or deionized water in their heating systems to address 7 common problems. Keywords: water treatment in heating systems, scaling in heating systems, corrosion in heating systems, disadvantages of using sponge iron for oxygen removal, operating costs of heating systems. Abstract: By using municipal tap water along with a multi-functional BF anti-corrosion and scale-inhibition agent, instead of sodium-ion resin-based softening equipment for producing softened water and removing oxygen, heating companies can significantly save water resources, industrial salts, electricity, and labor costs. This approach helps achieve energy conservation and emission reduction, improves efficiency, prevents contamination of groundwater resources, and protects the environment； It can also effectively address the long-standing problems in heating circulating water systems, such as corrosion, scaling, high water loss, and high operating costs. I. 7 Common Problems Related to the Use of Softened or Deionized Water in Heating Systems of Heating Companies. To prevent scaling in their heating systems, heating companies must soften the quality of the water used to supply water to these systems. The softening process can generally be divided into pre-heater treatment and in-heater treatment. At present, the feed water for industrial boilers in our country is mainly softened using industrial salt sodium-ion exchange resins, or desalinated water from reverse osmosis is used as make-up water for the system. In addition to preventing scaling, the water treatment in the heating systems of heating companies also needs to ensure corrosion protection for the entire heating system. There are three types of corrosion that can occur in such systems: oxygen corrosion, acidic corrosion caused by CO2, and under-scale corrosion. Heating companies that use softened water or deionized water in their heating systems often face seven common problems: industrial salts contaminating groundwater, oxygen corrosion and acidic corrosion of system equipment or pipelines, poor social benefits in terms of energy conservation and emission reduction, inadequate anti-corrosion protection when the systems are shut down, poor management of equipment operation, high operating costs for the systems, and severe human-induced water loss. 1. Common problems associated with the use of softened water in the heating systems of heating companies – Industrial salts contaminating groundwater. Sodium-ion exchange resins, which utilize industrial salts to soften water, are widely used in water treatment processes due to their advantages such as simple operation, stable water quality, easy maintenance, and low equipment costs. However, once the sodium ion exchange resin in water softening equipment becomes ineffective, it needs to be regenerated using industrial salt. Industrial salt used for regeneration requires large quantities, and the waste liquid resulting from its regeneration can contaminate groundwater by increasing its salt content. Heating companies use industrial salt sodium-ion resin water softening equipment in their heating systems; for every ton of softened water produced, about 2 kilograms of industrial table salt are discharged into the ground. Over time, the use of such equipment to soften water through sodium-ion resin will lead to an increase in salt content in groundwater, resulting in permanent salt contamination of that water. Industrial salt regenerants cause irreversible and permanent salt pollution of groundwater and surface water, which cannot be remedied. Simply the heating systems in large cities in the northern regions discharge over 50 million tons of table salt into the ground each year. People who drink groundwater with high salt content are prone to hypertension and heart diseases; the hazards caused by salt pollution are truly alarming! ▲The plate heat exchangers in the heat exchange stations of thermal power companies undergo traditional annual routine maintenance, which involves a large amount of work and results in high costs for cleaning and upkeep ； Corrosion in the heating system, as well as the formation of iron oxide scale on the plate exchangers, results in a low heat transfer rate. The heat transfer efficiency of iron oxide scale is only 1/200 to 1/300 that of steel. This scale not only reduces the efficiency of heat exchange and increases operating costs, but it also causes corrosion beneath it – namely pitting or crevice corrosion. Over time, this pitting or crevice corrosion deepens, eventually leading to perforations and leaks in the plate exchangers, with serious consequences as a result. 2. Common problems associated with the use of softened water or deionized water in the heating systems of heating companies – acidic corrosion of system equipment or pipelines. (1) Reverse osmosis-deionized water, having had all positive and negative ions removed from it and containing no calcium or magnesium compounds, has the advantage of not causing the formation of calcium or magnesium scale in heating systems. In recent years, thanks to the advanced development of industrial manufacturing in our country, the cost of production equipment as well as the operational and maintenance expenses associated with reverse osmosis desalinated or deionized water have continued to decline. As a result, a considerable number of heating companies now use reverse osmosis desalinated or deionized water in their heating systems. Since reverse osmosis demineralized or deionized water has had its positive and negative ions removed, it becomes extremely pure but lacks buffering capacity; the dissolution of even a small amount of CO2 can cause the pH level of the water in the system to drop, resulting in an acidic environment that can corrode the system’s equipment and pipelines. Experiments have shown that when 1 milligram of CO2 is added to 1 liter of demineralized or deionized water, its pH value drops from 7 to 5.5. Such a low pH level can cause acidic corrosion of the system’s equipment and pipelines. ⑵Heating companies use industrial sodium-ion resin to soften water in their heating systems. Sodium-ion exchange softens water by exchanging only the cations present in it, thereby removing the hardness caused by calcium and magnesium; however, it does not remove carbonate and bicarbonate ions (HCO3−). When these ions are heated, they decompose into CO2, which can cause corrosion in hot water boilers and other equipment in the heating system. This corrosion further releases CO2, which becomes a source of continuous corrosion. 3. Common problems associated with the use of softened water or deionized water in the heating systems of heating companies – oxygen corrosion of system equipment or pipelines. To be honest, the national standard GB/1576-2018 \"Water Quality for Industrial Boilers\" sets a requirement that the dissolved oxygen level in the water supplied to hot water boilers and heating systems should be ≤0.1 mg/L; this is actually a flaw in this standard. Firstly, there are currently no effective deoxygenation methods for hot water boilers and heating water systems. Although some heating companies use sponge iron for deoxygenation, this method introduces ferrous ions into the feedwater or make-up water, resulting in corrosion caused by these ferrous ions – a form of corrosion that is much more severe than that caused by dissolved oxygen. Since ferrous ions are also a source of cyclic corrosion, they exist in water in ionic form, which allows them to penetrate more easily into the metal surface of boilers and react with the metal, thereby accelerating its electrochemical corrosion. This type of corrosion not only affects the proper operation of boilers but can also shorten their lifespan and increase maintenance costs. Secondly, hot water boilers and heating systems do not require continuous water replenishment; the water storage tank is in communication with the atmosphere, and water that has had its oxygen removed differs in no way from water that has not had its oxygen removed after entering the tank. The use of the deoxidizer sodium sulfite yields poor deoxidation results; it not only increases the salt content in the system water, but sodium sulfite also deteriorates very easily during storage and use. There are numerous cases in practice where users employ ineffective sodium sulfite for water deoxidation, and its deoxidizing and anti-corrosion effects are inadequate. 4. Common problems with the use of softened water or deionized water in the heating systems of heating companies – poor social benefits in terms of energy conservation and emission reduction. The water consumption required to produce 1 ton of softened water using traditional sodium-ion exchange resin processes includes 0.03–0.06 tons of regeneration wastewater, along with a certain amount of backwash water; the exact amounts depend on the softening water treatment process employed and the operating conditions of the equipment. The water consumption required for producing desalinated water through reverse osmosis is greater than that for water softened with resins. The amount of water needed to produce 1 ton of desalinated water depends on various factors, including the quality of the raw water, the requirements for the output water, the efficiency of the equipment, and the design of the system. Generally, 0.6 tons of desalinated water are required for every 1 ton of aquatic products; the yield of water produced by primary reverse osmosis is 30%, with 70% of the water being concentrated waste water. For cascade filtration, the maximum water yield can reach 70%. 5. Common problems with the use of softened water or deionized water in heating systems of heating companies – Poor corrosion protection when the system is shut down. Heating companies operate on a periodic basis during the heating season; their heating systems are inactive for most of the year. When softened water or deionized water is used in such systems, there is no corrosion-inhibiting protection while the system is not in use. The corrosion rate of heating systems when they are shut down and not in operation is several times higher than when they are running. On the metal surfaces beneath the deposits in these systems, the oxygen content in water is relatively low, which leads to electrochemical unevenness on those metal surfaces. In areas with high dissolved oxygen concentrations, the electrode potential is high, making it a cathode; in areas with low dissolved oxygen concentrations, the electrode potential is lower, making it an anode, and it is at these sites that the metal corrodes. When the sediment contains soluble salts, these salts dissolve in the water film on the metal surface, increasing the salt content in that film. Due to the high electrical conductivity of solutions containing soluble salts, this accelerates oxygen-induced corrosion. Another major risk of corrosion due to shutdown is that it exacerbates the metal corrosion process during equipment operation. This is because corrosion of the shut-down equipment results in the formation of corrosive deposits on the metal surface, and the presence of these corrosion products along with the resulting roughness of the metal surface act as factors that promote increased corrosion beneath scale while the equipment is in operation. 6. Common problems with the use of softened water or deionized water in the heating systems of heating companies – Poor equipment operation management. The management of equipment used to produce softened water or deionized water in such heating systems is also a technical task; the level of equipment operation management affects the quality of the water produced. For example, inadequate backwashing of water softening equipment can lead to high chloride ion levels in the boiler water. Poor performance of scale inhibitors for desalination reverse osmosis membranes, or a mismatch with the quality of the raw water, can lead to a decrease in water production efficiency, a shortened lifespan of the reverse osmosis membranes, and an increase in the amount of concentrated wastewater generated. A few years ago, when I was at a customer’s facility, the person in charge of the boiler equipment shared his own practical experience. The heating steam boilers at that facility used softened water as make-up water. The industrial salt tank used for producing softened water did not have a mixer, and as a result, 1/4 to 1/3 of the tank’s capacity was always filled with undissolved industrial salt. During routine maintenance after shutting down the boilers each year, it was found that scaling had occurred in both boilers. Later, by chance, the industrial saltwater tank equipped with a stirrer was replaced, and since then, no scaling has occurred during the annual routine maintenance of the boiler. The manager in charge of this boiler equipment analyzed the reasons afterward; he had assumed that maintaining a water level of 1/4 to 1/3 unsolved salts in the industrial brine tank meant the solution was saturated, but this was not the case. In the absence of a stirrer, the concentration of this naturally dissolved solution is stratified, and it is not fully saturated. The concentration stratification of partially saturated salt solutions certainly has an impact on the efficiency of removing calcium and magnesium hardness from softened water; this is why scaling occurs in heating steam boilers during annual inspections. ▲A company in the north was carrying out maintenance on the heat exchangers in its heating system. The shell side of these exchangers was clogged with a mixture of iron oxide scale, calcium and magnesium scale, and biological sludge. When a small section in the middle was cleared by hand, more than 70 kilograms of dry scale fell to the ground. By comparing this with the worker shown in the photo, it’s possible to estimate how many kilograms of scale there are in total in this heat exchanger. With such poor heat exchange efficiency, what kind of pressure must the heating management team bear? How much additional energy will be consumed over one heating season? What do you think the increase in operating costs will be? 7. Common problems with the use of softened water or deionized water in the heating systems of heating companies – high operating costs. Whether heating companies use equipment to produce softened water or deionized water, costs such as water consumption, electricity consumption, chemical consumption, material costs (for example, large RO reverse osmosis membranes with a lifespan of 2 years cost around several thousand yuan), and labor costs for maintenance and management represent the basic fixed expenses associated with the operation of these systems, and these costs are quite substantial. Colleagues and fellow students, corrosion, perforation, leakage, natural and human-induced water loss, as well as scaling in heating systems have always been major problems for heating companies. How does your organization address these issues? Regarding issues such as boiler corrosion, scaling, and tube failure; corrosion in steam systems; regulation of pH levels in boiler feed water, furnace water, and steam condensate; red coloring of furnace water; hardness in steam condensate; excessive iron content in steam condensate; online descaling techniques that allow continued operation of the boiler without shutdown; and online cleaning and descaling techniques for condensers that enable continued operation without interruption, Yan Hui from Beijing University of Chemical Technology at I86OO475З86 is always ready to welcome colleagues to share their experience in managing and using boiler equipment, so as to learn from each other in addressing various practical problems related to boilers. Heating companies use tap water instead of softened water or deionized water in their heating systems to address 7 common problems. II. Heating enterprises use tap water instead of softened water or deionized water in their heating systems to address 7 common problems. Qingdao Kaiyuan Group’s Third Thermal Power Co., Ltd. operates 5 46MW hot water boilers; for many years, it has used municipal tap water, which is softened through sodium ion resin exchange before being used as make-up water. The quality of this softened water is satisfactory, and oxygen removal is carried out using sponge iron deoxidizers. However, the high rate of water loss necessitates frequent make-up water additions, resulting in severe corrosion of the plate heat exchangers as well as all the other equipment and pipelines in the system. This represents a serious problem that the company urgently needs to solve. In October 1999, the company used a multi-functional BF anti-corrosion and scale-inhibition agent developed under the leadership of Professor Wei Gang from Beijing University of Chemical Technology, an expert in metal corrosion prevention, in 5 46 MW hot water boiler systems, achieving excellent results. By shutting down the sodium-ion resin exchanger and the sponge iron deaerator, not only were the corrosion problems of the plate heat exchangers as well as the equipment and piping networks of the entire system resolved, but the issues related to accidental water loss and the protection of the system’s equipment and piping networks during shutdowns were also addressed. Several years of actual operation have shown that by adopting the multi-functional BF anti-corrosion and scale-inhibition agent technology, the thermal efficiency of boilers is significantly improved, energy savings are substantial, resulting in good economic and social benefits. 1. 12 advantages of the multi-functional anti-corrosion and scale-inhibition agent for BF boilers: (1) Anti-corrosion – the agent penetrates through scale and rust to form a protective layer on the metal surface, thereby preventing oxygen corrosion, CO2 corrosion, and corrosion beneath the scale; the corrosion inhibition rate is ≥99%. Scale inhibition: Scale inhibition efficiency ≥99%, wide range of effective inhibition, phosphorus-free formula as a substitute for trisodium phosphate ； ⑵As a wet shutdown protection agent, it provides a corrosion inhibition rate of ≥99% for protecting boiler and system equipment when they are not in use. It is sufficient to simply seal the boiler system equipment after shutdown, eliminating the need for frequent regular inspections. There is no need to drain the boiler water before starting or shutting down the boiler; it is suitable for long-term shutdowns, frequent start-up and shutdown cycles, as well as intermittent operation of boilers over extended periods ； ⑶As 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 ； ⑷Alkaline agents, used as pH regulators, raise the pH of feed water, system water, and boiler water so that the pH of the water system is ≥10; this keeps iron in a passivated state, neutralizes the weakly acidic corrosion caused by CO2, and minimizes corrosion. They serve as alternatives to sodium carbonate, sodium hydroxide, and ammonia. In recent years, due to the various shortcomings of using sodium carbonate or sodium hydroxide to adjust the pH value of boiler feedwater, more and more users are turning to alkaline water treatment agents—multi-functional BF corrosion and scale inhibition agents—to regulate the pH value of boiler feedwater ； ⑸It removes scale and deposits, as well as old deposits through chelation. The corrosion that occurs in hot water systems is primarily electrochemical corrosion. By eliminating the calcium and magnesium scales as well as iron oxide rust deposits in the water system, it removes the cathode involved in electrochemical corrosion, thereby preventing such corrosion. Chemicals are added to the system water, and proper waste discharge procedures are followed. The alkaline online cleaning of the equipment and piping networks is completed within 20–45 days, after which a protective coating is applied. The chemicals slowly and gently chelate and remove existing scale from the system; this process takes time, and it does not cause large amounts of scale to break off and block the pipes in a short period. This method replaces the traditional acid cleaning used for boiler maintenance, allowing for damage-free online cleaning of the boiler system without the need to shut it down. As a result, the circulating water remains clean and clear, while the inner surfaces of the system equipment and piping networks stay smooth and clean. The plate heat exchangers in the heat exchange stations do not need to be disassembled, repaired, or cleaned, thus maintaining their high thermal efficiency ； ⑹To prevent artificial water loss, the addition of BF anti-corrosion and scale-inhibiting agent results in a light tea-colored circulating water, which effectively prevents artificial water loss ； ⑺Used as an antifoaming agent to increase steam dryness and ensure steam quality ； ⑻Raw water + BF corrosion and scale inhibition agent; hot water boilers instead of softened water; deoxygenation process to protect the environment ； ⑼Raw water + BF corrosion and scale inhibition agent + BF condensate protection agent, replacing the softening unit + deaeration equipment + iron removal equipment in steam boiler systems ； ⑽Simple operation: Add the chemical to the water replenishment tank; a pH value of 10.5–12 for the water in the boiler is considered acceptable ； ⑾The multi-functional BF anti-corrosion and scale-inhibition agent possesses chelating properties for scale removal as well as a film-forming function; it provides significant drag reduction, saving more than 30% on the electricity consumption of circulation pumps, with the savings exceeding the cost of using the chemical ； ⑿The 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’s blowdown rate. When BF anti-corrosion and scale-inhibiting agents are used in the heating systems of heating companies, they can, while the system is in operation, remove existing scale, disperse iron oxide scale for rust removal, provide corrosion protection, form a protective layer, and prevent accidental water loss. This leads to energy savings, water savings, salt savings, and an extension of the service life of equipment and pipelines by more than 5 times; it also significantly reduces the amount of maintenance required and associated costs. In heating systems, this can result in 20%–45% energy savings, ≥20% electricity savings, 1–multiple times greater water savings, and 40%–85% salt savings. Typically, the cost-benefit ratio of these agents is over 1:100, meaning that an investment of 1 yuan in these agents generates economic benefits worth over 100 yuan. 2. Estimation of economic benefits after adopting the anti-corrosion and scale-inhibition agent technology for multi-efficiency BF boilers: Based on the annual heating period targets, the use of this technology in 17 thermal stations serving an area of 3 million square meters enables savings of 3 million kWh of electricity, equivalent to 1.56 million yuan ； 240,000 tons of water saved, equivalent to 670,000 yuan ； Savings of 120,000 yuan can be achieved in terms of industrial salt, and approximately 200,000 yuan can be saved on the wages of staff at the heat station. In total, this amounts to a savings of 2.55 million yuan. Additionally, by using the anti-corrosion and scale-inhibition agent for multi-functional BF boilers, corrosion of the equipment and pipes in the entire heating water system is prevented, which significantly reduces the workload for workers as well as maintenance costs. Maintenance costs can be reduced by more than 2 yuan per square meter. Within 2 years, the heating system can enter a sustainable cycle, resulting in savings of around 6 million yuan in maintenance costs for the equipment and pipelines. The total economic benefit resulting from the use of this anti-corrosion and scale-inhibition agent technology exceeds 8.55 million yuan (without deducting the cost of the agent itself). III. Conclusion: By using municipal tap water along with a multi-functional BF anti-corrosion and scale-inhibition agent in the heating systems of heating companies, instead of sodium-ion resin softening equipment for producing softened water and removing oxygen, it is possible to significantly save water resources, industrial salts, electricity, and labor, thereby achieving energy conservation and emission reduction as well as preventing contamination of groundwater resources. Additionally, this approach can greatly reduce the salt content and alkalinity in the raw water, converting calcium and magnesium ions as well as alkalinity into substances that are beneficial for plant growth, thus helping to protect the environment ； It can also effectively address the problems of corrosion and scaling in heating circulating water systems ； It can prevent corrosion and scaling of the equipment and pipelines in the boiler heating system during operation and when it is not in use, thereby protecting and extending their service life; it also eliminates potential safety hazards in the boiler system’s equipment and pipelines caused by corrosion, perforations, leaks, etc. Using multi-functional BF corrosion and scale inhibition agents is a simple, effective, economical, environmentally friendly, and energy-saving water treatment method for heating system water treatment in heating enterprises. Heating companies use tap water instead of softened or deionized water in their heating systems to address 7 common problems (Yan Hui)