Summary of Chemical Deoxygenation Operation for Boiler Feed Water

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I. Purpose of the commissioning II. Product introduction III. Hazards of oxygen corrosion IV. Commissioning process and data V. Economic benefit analysis VI. Conclusions VII. Appendix: Commissioning data and explanations from November 30 to December 13, 2017 I. Purpose of the commissioning: The company’s three 150-ton/hour circulating fluidized bed boilers are medium-high pressure boilers. Under normal operation, the dissolved oxygen level in the feed water to the steam drum is approximately 80 μg/L, which is higher than the standard value of 15 μg/L specified in the standards for water and steam quality in thermal power generation units and steam-powered equipment (GB/T12145-2008). Oxygen corrosion occurs in these systems, posing a serious threat to the boiler equipment and causing significant harm to the long-term operation of the boiler system. At the same time, in order to reduce the dissolved oxygen in the boiler feedwater, it is necessary to raise the deoxygenation temperature above 150 degrees, which increases the consumption of deoxygenation steam; this in turn leads to a shortage of steam supply from the boiler when the steam production load is high. To address the above issues, the company collaborated with chemical deoxidizing agent manufacturers on two occasions: from November 30 to December 13, 2017, and from November 23 to November 27, 2018, to conduct tests on the safety of these deep deoxidizing agents, their reliability in removing oxygen, and their energy-saving effects. II. Introduction to Deep Deoxidizer Products: The deoxidizer is composed of advanced organic deoxidants, corrosion and passivation inhibitors, as well as acid-base balance agents. It can effectively and rapidly remove dissolved oxygen from the feed water, thereby passivating the metal surface and preventing metal corrosion. This product can assist in further reducing the residual dissolved oxygen content in feed water through thermal deoxidation, enabling it to meet **standard requirements (GB/T12145-2008), while also allowing the equipment system to operate under safer and more economical conditions. Furthermore, the active component in the deoxidizer can react with metal oxides such as copper and iron present in the system, thereby passivating the metals and providing corrosion inhibition and passivation effects; it enables the formation of a dense Fe3O4 protective layer on the metal surface. It is a new type of efficient boiler feedwater deoxidizer and anti-corrosion/anticorrosive agent that provides thorough protection for the boiler system without affecting its heat transfer capabilities. Suitable for steam boilers, thermal power generation units, etc., with operating pressures ranging from 3.8 to 9.8 MPa. III. Hazards of oxygen corrosion 1. Oxygen corrosion is the most common and severe form of corrosion in boiler systems. When dissolved oxygen enters the boiler along with the feedwater, it causes corrosion to various parts of the boiler, such as the boiler itself and the feedwater piping network, under the boiler’s operating temperature and pressure. This corrosion can take the forms of chemical corrosion, electrochemical corrosion, or concentration cell corrosion, leading to defects such as ulcers and perforations. It severely damages the strength of the metals, and is an important factor affecting the safety and service life of boilers. In boiler water systems, when metal comes into contact with dissolved oxygen, due to the unevenness of the metal surface and the electrical conductivity of the water, many corrosion microcells form on the metal surface. In the anode and cathode regions of these microcells, the following oxidation reactions occur: in the anode region: Fe → Fe2+ + 2e; in the cathode region: 1/2O2 + H2O + 2e → 2OH-. The corrosion resulting from these reactions is known as oxygen depolarization corrosion, or simply oxygen corrosion. When iron is corroded by dissolved oxygen, Fe2+ is produced. The secondary reactions that occur in water are as follows: Fe + 1/2O2 + H2O → Fe(OH)2; 4Fe(OH)2 + O2 + 2H2O → 4Fe(OH)3. Boiler corrosion is primarily caused by the corrosion resulting from dissolved oxygen in water. Oxygen corrosion is characterized by pitting corrosion, with corrosion pits forming gradually; in severe cases, this can lead to perforation, posing a serious threat to the safe operation of boilers. Its main corrosion sites are the heating surfaces such as the economizer and downcomers. All 3 boilers in the company are medium-high pressure boilers with an operating pressure of 5.32 MPa. Once corrosion occurs inside these devices, it is more likely to cause equipment damage and pipe bursts compared to low-pressure boilers, posing a serious threat to the safety of operators on site and creating significant risks to the safe operation of the boilers. 2. After oxygen corrosion occurs in the boiler, the level of Fe3+ in the boiler water increases significantly. As the boiler operates, scale is formed. Iron scale adheres to the heated surfaces, affecting the heat transfer in the boiler and resulting in reduced thermal efficiency as well as increased operating costs. After scale adheres to the surface of equipment, under-scale corrosion occurs, which, just like oxygen corrosion, poses a threat to the safe operation of boilers. 3. The quality of deoxygenation in a boiler has a direct impact on its service life. If the deoxygenation is inadequate, oxygen corrosion occurs; as the boiler operates, the failure rate increases significantly, maintenance workloads rise, maintenance costs increase, and the number of shutdowns increases, all of which severely affect production efficiency. As a result, the service life of boilers also decreases significantly; many boilers are scrapped ahead of time due to oxygen corrosion, failing to pass the annual inspections. IV. Debugging Process and Related Quality Records 1. From 14:00 on November 23, 2018, to 11:00 on November 24, 2018, technicians from the chemical company went to the site to work together with the company’s production department and workshop technicians to collect data on the operating conditions of the company’s boiler system. They also measured the dissolved oxygen level in the feed water, and recorded the operational data of the system before any chemicals were added. 2. From 12:00 on November 24th to 10:00 on November 26th, this period was used for testing the deep deoxidizer supplied by the chemical supplier. 3. From 10:00 on November 26th to 16:40 on November 27th, these records show the operation of the deaerator at a temperature of around 104°C, with the oxygen content in the feed water to the steam drum remaining at ≤15μg/L throughout this period. The above describes the debugging process. The specific quality records are shown in the table below:
Table 1: Data recording sheet for the company’s deep deoxygenation process
Time | Deoxygenation temperature (°C) | Oxygen content (μg/L) | Remarks
1# | 2# | 1# | 2#
11.23 | 14:00 | 115.9 | 115.1 | 43.9 | 98.6
15:00 | 118.0 | 116.8 | 127.1 | 91.3
16:00 | 114.7 | 113.3 | 112.0 | 87.0
17:00 | 118.0 | 116.0 | 122.0 | 86.0
18:00 | 115.2 | 113.2 | 50.1 | 32.0
19:00 | 116.3 | 115.9 | 123.0 | 76.0
20:00 | 117.4 | 116.0 | 85.3 | 62.6
21:00 | 115.2 | 113.6 | 64.5 | 47.8
22:00 | 118.0 | 116.5 | 58.3 | 45.6
23:00 | 117.2 | 115.8 | 64.3 | 40.7
24:00 | 117.0 | 115.6 | 58.2 | 14.2
11.24 | 8:00 | 118.0 | 116.9 | 72.0 | 42.6
9:00 | 117.4 | 116.2 | 52.3 | 28.5
10:00 | 119.7 | 118.6 | 79.7 | 38.3
11:00 | 116.0 | 115.0 | 72.1 | 43.7

The above data were collected during a period when the operating temperature of thermal deoxygenation was maintained between 113°C and 118°C; this phase lasted for a total of 21 hours.
11.24 | 12:00 | 116.0 | 114.5
At 11:40, a deoxidizer was added, and the oxygen content in feedwater was monitored at the economizer inlet.
13:00 | 119.3 | 117.9 | 7.3
14:00 | 115.0 | 113.0 | 3.5
15:00 | 118.0 | 116.0 | 13.0
15:30 | 117.7 | 116.5 | 0.5
16:00 | 117.3 | 116.0 | 2.7
17:00 | 118.8 | 117.6 | 0

11.25 | 8:00 | 117.5 | 116.3 | 15.0
9:00 | 116.8 | 115.5 | 1.5
10:00 | 116.5 | 115.5 | 3.0
11:00 | 118.6 | 117.3 | 10.0

The above data were collected during a phase when the operating temperature of thermal deoxygenation remained between 113°C and 118°C while a deoxidizer was being added; this phase lasted for 24 hours in total.
11.25 | 12:00 | 114.1 | 112.8 | 24.0
13:00 | 113.8 | 112.6 | 12.0
14:00 | 112.0 | 110.6 | 3.5
15:00 | 110.5 | 109.0 | 8.6
16:00 | 111.7 | 110.5 | 5.0
17:00 | 112.0 | 110.0 | 4.8

11.26 | 8:00 | 111.6 | 110.1 | 8.0
9:00 | 115.0 | 113.6 | 2.9

The above data were recorded during a phase where the deaerator temperature was gradually lowered while a deoxidizer was added; this phase lasted for 21 hours in total.
11.26 | 10:00 | 104.0 | 103.0 | 11.5
11:00 | 107.1 | 106.0 | 9.0
12:00 | 103.2 | 101.8 | 10.3
13:00 | 106.2 | 105.0 | 16.0
14:00 | 103.0 | 102.0 | 12.0
15:00 | 103.0 | 102.1 | 13.1
16:00 | 103.6 | 101.7 | 12.7
17:00 | 106.0 | 104.0 | 9.5

11.27 | 8:00 | 103.4 | 102.2 | 15.4
9:00 | 104.0 | 103.0 | 13.9
10:00 | 104.6 | 103.5 | 11.4
11:00 | 103.6 | 102.2 | 11.7
12:00 | 102.0 | 100.7 | 8.0
13:00 | 103.4 | 101.7 | 9.7
14:00 | 103.0 | 101.5 | 10.5
15:00 | 103.2 | 101.7 | 12.3
16:00 | 102.1 | 100.8 | 16.0
17:00 | 103.2 | 102.2 | 4.6

The above data were collected during a phase when the operating temperature of the deaerator was kept between 101°C and 104°C while a deoxidizer was added; this phase lasted for 31 hours in total.

Data explanation: From 14:00 on November 23 to 11:00 on November 24, the data represent the dissolved oxygen content under conditions of thermal deoxygenation alone. After that point, the values reflect the dissolved oxygen content after the addition of a deep deoxidation agent. As can be seen from the table, under conditions of thermal deoxygenation alone, when the temperature is around 118°C, the dissolved oxygen content in feedwater generally remains within the range of 70–140 μg/L, with occasional fluctuations. It far exceeds the national standard requirements. From 2:00 p.m. on November 23 to 11:00 a.m. on November 25 (a total of 45 hours), the average operating temperature of the deaerator during this period was 117.6°C. A total of 1,613.8 tons of steam were used for thermal deaeration, with an average consumption of 35.9 tons of steam per hour ； 3. From 10:00 on November 26 to 17:00 on November 27 (a total of 31 hours), the average operating temperature of the thermal deaerator was 103.8°C, and a deoxidizer was used to assist in deoxygenation. After using a high-efficiency deoxidizer, the dissolved oxygen level dropped significantly, remaining below 15 μg/L, thus meeting the national standards (according to the water quality standards for thermal power generation units specified in 12145-2008, the dissolved oxygen in feedwater should be ≤15 μg/L). A total of 822 tons of steam were used for thermal deaeration, with an average consumption of 26.5 tons per hour ； 4. After the adjustments were completed, relevant company personnel and those from the chemical supplier jointly tested the dosage of the chemicals used and the deoxygenation effect, in order to ensure the accuracy of the data. 5. Starting from the 24th, deep deoxidizers were used. Personnel from the chemical supplier, together with those from the company’s production department and workshops, collected data on the deoxidization effect and steam volume. From 10:30 to 16:40 on the 27th, relevant personnel from the branch company and technical staff from the chemical supplier monitored in real time the amount of chemicals added as well as various quality records. While keeping the dissolved oxygen level in the feedwater at the boiler economizer inlet below 15 micrograms per liter, they recorded the amounts of chemicals used and the steam output. The specific data are shown in the table below: Table 2: Real-time monitoring of the amount of deep deoxidization chemicals used and boiler load statistics. Time, Location: Liquid level in the chemical tank at the inlet of Pump No. 2 (cm), Liquid level in the chemical tank at the inlet of Pump No. 3 (cm), Liquid level in the chemical tank at the inlet of Pump No. 4 (cm), Cumulative steam output of Boiler No. 1 (tons), Cumulative steam output of Boiler No. 2 (tons), Cumulative steam output of Boiler No. 3 (tons). Initial liquid levels at 10:30: 33.5, 29.6, 63.98; Cumulative steam outputs: 244, 575, 973, 795, 13. Final liquid levels at 16:40: 28.4, 23.75, 2.08; Cumulative steam outputs: 294, 467, 669, 580, 267. Total amounts used: 5.1, 5.9, 11.95; Total steam output: 501, 722, 754 tons. Overall total: 22.91977 tons of steam. Amount of chemicals required: 22.9 cm ÷ 9.5 cm/bucket × 25 kg/bucket = 60.2 kg. 60.2 kg ÷ 1977 tons = 30.4 g per ton of steam. Note: The standard amount of chemicals per bucket is 9.5 cm, which corresponds to 25 kilograms (this measurement was determined through on-site testing, with company personnel present throughout the process). V. Economic benefit analysis: From November 23 to November 27, 2018, an economic analysis was conducted regarding the use of deep deoxidization agents. The amount of steam consumed for deoxidization before and after using these agents was recorded, as follows: From 2:00 p.m. on November 23 to 5:00 p.m. on November 24 (a total of 45 hours), the average temperature for thermal deoxidization was 117.6°C. Before any cooling took place, the boiler consumed a total of 1613.8 tons of steam for its own use. The steam consumption per hour is: 1613.8 tons ÷ 45 hours = 35.9 tons. 2) From 10:00 on November 26th to 17:00 on November 27th (a total of 31 hours), the average temperature in the thermal deaeration process was 103.8°C; under the condition that the dissolved oxygen level was within acceptable limits, a total of 822 tons of steam were consumed. The amount of steam consumed internally per hour is: 822 tons ÷ 31 hours = 26.5 tons. During this period, the three boilers produced a total of 9861 tons of steam; the steam production rate per hour was therefore: 9861 tons ÷ 31 hours = 318 tons. 3) Daily savings (with steam priced at 100 yuan per ton): Savings from reducing internal steam consumption: (35.9 – 26.5) tons/hour × 100 yuan/ton × 24 hours/day = 22,560 yuan/day. Cost associated with using deep deoxidizers: 30.4 g/t of water × 318 tons/hour × 24 hours/day × 42 yuan/Kg = 9,744.5 yuan/day. Net savings: 22,560 yuan/day – 9,744.5 yuan/day = 12,815.5 yuan/day. All the figures mentioned above are derived from the data recorded on the company’s workshop DCS system. 2. From November 30 to December 13, 2017, during the period of testing the economic effects of using deep deoxidizers, the amount of steam consumed for deoxidization was recorded. The statistics are as follows: 1) Before the addition of the deoxidizer: from 8 a.m. on December 1 to 4 a.m. on December 7; at that time, the temperature for thermal deoxidization was around 121°C, and a total of 4,260 tons of steam were consumed for deoxidization before the addition of the deoxidizer. The steam consumed by the three boilers per hour is: 4260 tons ÷ 140 hours = 30.4 tons. 2) After adding chemicals: from 10:00 on December 7th to 9:00 on December 13th, a total of 143 hours. During this period, from 16:00 on the 9th to 10:00 on the 10th, due to a significant drop in temperature and in the absence of insulation on the deaerator exhaust pipes, the temperature of the deaerator was temporarily increased to prevent freezing; this lasted for 19 hours. The data from this period needs to be excluded. For the remaining 124 hours, the temperature in the thermal deaeration process remained around 100–104 degrees, resulting in a total consumption of 2200 tons of steam (the total steam consumed over 143 hours was 2642 tons, with 442 tons corresponding to the period when the temperature was increased). Steam consumed internally per hour: 2200 ÷ 124 hours = 17.7 tons. 3) Daily savings (at a cost of 100 yuan per ton for steam): Savings from reducing internal steam consumption: (30.4 – 17.7) × 100 yuan/ton × 24 hours = 30,480 yuan per day. Cost of using deep deoxidizers: 36 g/t water × 318 tons/h × 24 hours × 42 yuan/Kg = 11,540 yuan per day. Net savings: 30,480 yuan – 11,540 yuan = 18,940 yuan per day. Note: Relevant calibration data and explanations are provided in Appendix 3. The estimate for energy savings from using chemical agents for deoxidation in summer is based on the company’s historical data; during summer, the company typically operates 2 boilers, with an average steam production of 260 tons per hour, which is approximately 80% of the steam production in winter. (The calculations below are based on the data from the debugging period from November 23 to November 27, 2018.) With chemical deoxidization, steam can be saved at a rate of 9.4 tons/h × 80% = 7.52 tons/h. The cost savings in terms of steam consumption amount to 7.52 tons/h × 100 yuan/ton × 24 h/day = 18,048 yuan/day. The cost associated with using advanced deoxidizing agents is 30.4 g/t of water × (260 – 7.52) tons/h × 24 h/day × 42 yuan/Kg = 7,736.8 yuan/day. The net cost savings amount to 18,048 yuan/day – 7,736.8 yuan/day = 10,311.2 yuan/day. 4. Changes in the water temperature at the exit of the economizer: When thermal deoxidization is used, the boiler feedwater temperature is around 118°C, which is higher than that when chemical deoxidization is used (around 104°C). However, since cooler water entering the economizer and boiler can absorb more heat from the boiler’s flue gases, this 14°C difference can be compensated for by absorbing more heat. Based on the data from November 23 to November 27, 2018, it can be seen that when the deaerator operated at 104°C and 118°C, the water temperature at the outlet of the economizer fluctuated between 220°C and 230°C, showing no tendency to decrease. VI. Conclusion Based on the analysis of data from the two debugging sessions, comparing deep deoxidization using deep deoxidizers with heat-based deoxidization methods reveals the following advantages of the latter: 1. Over the course of the two experiments, which lasted for more than 10 days in total, 3.2 tons of chemicals were used. During this period, the production volume and quality of the company’s products remained stable, which clearly demonstrates that the use of deoxidizers had no adverse effects on the company’s boiler systems, products, or production processes. 2. Ensure that the dissolved oxygen content in the boiler feed water meets the requirements specified in the **standard (GB/T12145-2008)** ； Long-term use can form a complete and dense protective film on the metal surface, effectively slowing down or preventing corrosion in thermal systems, thereby ensuring the safe and economical operation of boiler systems. 3. It reduces the consumption of steam used for thermal deaeration, thereby cutting coal usage; the cost of chemicals used is less than 50% of the savings resulting from reduced steam consumption, which lowers production costs. 4. Fast deoxygenation speed, strong stability, and significant effects ； 5. It is easy to operate, allows for precise dosing, and is simple to manage. During the two debugging periods, the chemical company deployed 6 technicians in total (8 person-times), prepared 4 tons of debugging chemicals, and supplied 4 sets of dosing equipment (4 dose pumps imported from Italy and 4 dosing tanks). The total debugging time was 21 days, with over 1,800 sets of debugging data recorded. More than 300,000 yuan was spent on the two rounds of debugging (including chemicals, shipping costs, personnel travel expenses, accommodation, etc.). Through these two successful debugging sessions, the company gained a clearer and more comprehensive understanding of the deoxygenation efficiency and energy-saving potential of chemical deoxygenation, which ultimately led to friendly cooperation between the supplier and the customer for mutual benefit. VII. Appendix: Commissioning data and explanations from November 30 to December 13, 2017
Time | Deaerator temperature (°C) | Dissolved oxygen (μg/L) | Remarks
1# | 2# | 3# | 1# | 2#
11/30 | 10:00 | 119 | 115 | 117 | 200 | 204
14:00 | 119 | 116 | 118 | 214 | 194.6
15:00 | 115 | 110 | 114 | 129.5 | 111
12/01 | 19:00 | 123 | 117 | 122 | 142.3 | 135.1
10:00 | 123 | 117 | 122 | 139.6 | 132.8
14:00 | 127 | 120 | 126 | 95.5 | 58.4
15:00 | 128 | 121 | 126 | 64.6 | 69.2
12/02 | 08:00 | 126 | 119 | 124 | 124.0 | 125.3
10:00 | 126 | 119 | 125 | 113.9 | 110.3
14:00 | 127 | 119 | 125 | 97.9 | 83.0
15:00 | 124 | 116 | 122 | 91.0 | 79.2
12/03 | 08:00 | 124 | 117 | 122 | 128.6 | 135.9
10:00 | 126 | 118 | 124 | 134.6 | 140.7
13:00 | 124 | 117 | 122 | 22.0 | 122.6
14:00 | 123 | 118 | 120 | 133.5 | 133.3
15:00 | 122 | 115 | 120 | 24.1 | 125.7
12/04 | 08:00 | 125 | 119 | 123 | 29.6 | 132.6
10:00 | 125 | 119 | 123 | 32.4 | 110.5
14:00 | 125 | 120 | 123 | 63 | 135.2
16:00 | 126 | 119 | 124 | 22.5 | 69.1
12/05 | 08:00 | 128 | 122 | 126 | 22.6 | 141.2
09:00 | 127 | 120 | 125 | 75 | 134.1
10:00 | 127 | 120 | 125 | 97.7 | 126.5
14:00 | 126 | 120 | 124 | 92.5 | 135.8
15:00 | 125 | 120 | 123 | 13.4 | 99.0
12/06 | 08:00 | 122 | 115 | 121 | 48.7 | 123.4
11:00 | 123 | 116 | 121 | 17.4 | 137.2
14:00 | 127 | 119 | 125 | 45.7 | 131.5
15:00 | 126 | 118 | 124 | 43.4 | 127.6
The above data represent dissolved oxygen levels prior to chemical dosing. On December 7 at 10:00, deep deoxidation agents were introduced for commissioning purposes.
12/07 | 11:00 | 104 | 98 | 103 | 56.6 | –
Maintenance work was carried out at sampling point 3; pump No. 3 had become clogged due to crystallization.
12:00 | 106 | 100 | 105 | 50.00 | Maintenance at sampling point
14:00 | 105 | 99 | 104 | 40.00 | Maintenance at sampling point
15:00 | 106 | 101 | 105 | 50.00 | Maintenance at sampling point; dosage began to be reduced thereafter.
08:00 | 106 | 100 | 104 | 35.5 | Maintenance at sampling point
09:00 | 104 | 98 | 102 | 20.00 | Maintenance at sampling point
After 09:00, cooling units were installed at sampling points 1 and 2; measurements could not be taken until the evening of the 8th. 12.09: 00 – 102951000.00 Repair of sampling points; 9:00 – 101941000.00 Repair of sampling points; 10:00 – 104971034.83.0; 11:00 – 104971037.96.3; 13:00 – 105971030.001.0; 14:00 – 104971037.95.6; 15:00 – 104961024.00.9; 16:00 – 103951022.70.00.
12.10: 00 – 1121051113.70.00; 9:00 – 1121051114.70.00; 10:00 – 107991052.60.00; 11:00 – 107991053.90.00; 12:00 – 106981047.30.8; 13:00 – 1059810417.913.2. The level of dissolved oxygen exceeded the limit; thus, it was impossible to further reduce the dosage of chemicals. 14:00 – 1059810418.713.4; 15:00 – 104981034.70.00; 16:00 – 106991043.90.00.
12.11: 8:00 – 1059810312.30.00; 9:00 – 104981039.72.1; 10:00 – 1061001045.81.6; 11:00 – 104981039.25.9; 13:00 – 104981037.98.4; 14:00 – 104981036.37.6; 15:00 – 1061001047.88.3; 16:00 – 105991046.88.7.
12.12: 8:00 – 10610110535.320.93. Crystallization caused blockage in #3 chemical dosing pump; 9:00 – 1061011059.911.3; 10:00 – 10610110510.110.9; 11:00 – 10410010312.611.7; 13:00 – 10610110411.310.7; 14:00 – 103991027.810.2; 15:00 – 103981019.37.5; 16:00 – 102981018.97.4.
12.13: 9:00 – 1059910317.521.33. Crystallization caused blockage in #3 chemical dosing pump; 10:00 – 104981029.813.6; 11:00 – 1049810212.513.7; 13:00 – 104991037.38.6; 14:00 – 103981025.70.00. At 2 p.m. on the 13th, due to production requirements, the company reduced the boiler load. The operating conditions changed, rendering the data meaningless. Data explanation: Deoxidizers were started to be used on December 7; prior to that, the dissolved oxygen level corresponded to that achieved through single thermal deoxidation, while after the use of these deoxidizers, it reflected the dissolved oxygen level after additional deoxidization. As can be seen from the table, under single thermal deoxidation conditions, at a temperature of around 121°C, the dissolved oxygen level in the feedwater remained generally between 90 and 140 μg/L, with fluctuations occurring; the lowest value was around 70 μg/L, and the highest was around 200 μg/L. It far exceeds the national standard requirements. After using a deep deoxidizer, the dissolved oxygen level dropped significantly, remaining below 15 μg/L, thus meeting the national standards. (According to the water quality standards for thermal power generation units specified in 12145-2008, the dissolved oxygen content in the feedwater shall be ≤15 μg/L.) 2. The dates of December 7th and 9th are designated as adjustment phases: during this period, an excess amount of chemicals is added to ensure that the oxygen content in the feedwater at the inlet of the economizer of each boiler is 0 micrograms per liter; thereafter, the amount of chemicals added is gradually reduced while the oxygen content is continuously monitored. Once the oxygen content meets the required standards, the chemical addition system is optimized to ensure that the dissolved oxygen content in the feedwater to the steam drum of each boiler remains below 15 micrograms per liter. 3. After the adjustments were completed, the chemical company, together with the relevant personnel of the company, tested the dosage of the chemicals and the deoxygenation effect to ensure the accuracy of the data. 4. Starting from the 7th, deep deoxidizers were used. At 10:00 on the 9th, once the oxygen levels at the inlets of the economizers in all three boilers were within acceptable limits, personnel from the chemical supplier, together with representatives from the company’s production department, technical department, and workshops, began to collect data on drug consumption, deoxidization efficiency, water volume, and steam output. From 10:00 a.m. to 2:15 p.m. on the 12th, continuous monitoring was carried out; the dissolved oxygen level was kept below 10 micrograms per liter while data on the amount of drug used, water volume, and steam output were recorded. The specific data are shown in the table below: Location: Liquid level in the chemical tank at the inlet of Pump No. 2; Liquid level in the chemical tank at the inlet of Pump No. 3; Liquid level in the chemical tank at the inlet of Pump No. 4; Cumulative steam output of Boiler No. 1 (tons); Cumulative steam output of Boiler No. 2 (tons); Cumulative steam output of Boiler No. 3 (tons). Initial liquid level (cm): 45.5, 57.5, 26.17, 44.51, 78.39, 99.996. Final liquid level (cm): 38.35, 146.56, 217.35, 182.62, 90.49, 292. Consumption (output): 7.26, 5.54, 294.23, 496 tons. Amount of drug used per ton of water: 36 grams. Note: The standard amount of drug required per 9.5 cm of liquid level is 25 kilograms