Air Preheater/GGH

Qixing Power provides high-quality air preheaters and flue gas heat exchangers as complete sets to the power market. With years of experience and leading-edge technology in the forming and shearing of heat-exchange elements, enamel coating processes, and enamel firing techniques, our products have consistently earned the strong appreciation and trust of a wide range of customers. We primarily offer the following product series: 1. Electrostatic dry-process enamel-coated heat-exchange elements for air preheaters; 2. Wet-process enamel-coated heat-exchange elements for air preheaters; 3. Corten steel heat-exchange elements for air preheaters; 4. Conventional steel heat-exchange elements for air preheaters; 5. Sealing components for air preheaters; 6. Sector plates and arc-shaped plates for air preheaters; 7. Complete sets of soot-blowing and high-pressure water-cleaning equipment for air preheaters; 8. Electrostatic dry-process enamel-coated heat-exchange elements for flue gas heat exchangers; 9. Wet-process double-coat enamel elements for flue gas heat exchangers; 10. Sealing components for flue gas heat exchangers; 11. Complete sets of soot-blowing and high-pressure water-cleaning equipment for flue gas heat exchangers; 12. Tube-type air preheaters without sleeves; 13. Inner-enamel-coated tube-type air preheaters and outer-enamel-coated tube-type air preheaters; 14. Specialized inner-enamel-coated and outer-enamel-coated tube-type air preheaters for flue gas denitrification in steel plants; 15. Corten steel tube-type air preheaters; 16. Enamel-coated ash-conveying pipelines and enamel-coated internal lining components for chimneys. The outstanding performance of Qixing Power’s products has been validated over more than a decade, and our excellent reputation and customer trust are built on this solid foundation. Our products are characterized by: 1. High-quality raw materials; 2. Cost-effectiveness suited to various applications; 3. Excellent value for money; 4. Long-lasting durability; 5. Highly efficient heat exchange performance; 6. Superior weather resistance.

Use and Maintenance

Heat Exchanger Component Lifting: The heat exchanger components provided by Qixing Power generally come in two materials. One is a low-carbon steel plate component with a thickness ranging from 0.5 to 0.6 mm, used on the hot end; the other is an enamel-coated component with a coating thickness between 1.15 and 1.2 mm, used on the cold end. Since these heat exchanger components are all rolled from thin plates, during transportation and lifting, it is crucial to avoid damaging the component ends. Otherwise, issues such as component deformation or enamel peeling may occur. Typically, Zhongneng Jiyе provides a set of specialized lifting tools specifically designed for handling heat exchanger component boxes. The use of self-made, ordinary carbon steel lifting tools is strictly prohibited! Due to the poor fatigue resistance of carbon steel, such tools are prone to hook detachment or fracture, which could lead to serious safety accidents. Heat Exchanger Component Transportation and Storage: During loading and transportation, heat exchanger components must be neatly stacked and securely fastened with protective netting and covered with waterproof tarps. Before unloading, any accumulated rain or snow on the tarp should be shaken off outside the vehicle—never allowed to fall onto the components themselves. The stacking area for heat exchanger components must be free of standing water and debris, elevated above surrounding ground levels, and protected with waterproof tarps. Loading and unloading of heat exchanger components should never be carried out in rainy weather, as this could cause corrosion. Heat Exchanger Component Installation Protection: During installation, avoid contact between the heat exchanger components and metal objects such as structural steel columns, electric hoist hooks, and guide chains. When lifting the components into the housing, always check the stability of the supporting steel bars and remove any welding slag, scrap metal, and other debris. After the components are placed into the housing, lay asbestos blankets one by one to protect the component ends and prevent damage during subsequent installation steps! Dust and Corrosion Control for Components: In practice, almost all fuels burned in boilers contain sulfur. During combustion, 2% to 6% of sulfur dioxide is converted into sulfur trioxide, which reacts with water vapor in the flue gas to form ammonium bisulfate—a compound resulting from the reaction between ammonia escaping from the denitrification system and sulfur trioxide. On the surface of cold-end heat exchanger components, this leads to the formation of a sticky, corrosive deposit. Additionally, fly ash in the flue gas and particulate matter generated during sootblowing can further damage the components, causing continuous corrosion, blockage of heat transfer channels, reduced heat exchange efficiency, shortened service life, and high pressure drop. To effectively control and slow down corrosion and blockage of cold-end heat exchanger components, it is essential to keep ammonia escape rates below 2.3 mg/m³; ensure that the SO₂/SO₃ conversion rate does not exceed 1% (molar ratio); avoid prolonged operation of the air preheater at temperatures below the recommended minimum "combined cold-end temperature" (flue gas outlet temperature + air inlet temperature); and promptly repair any leaks in the economizer or air heater that might increase the dew point of the flue gas. Fire Prevention Measures: During ignition, low-load operation, and poor combustion conditions, incompletely burned coal dust and oil residues used for ignition can lead to secondary combustion. Therefore, it is critical to prevent the accumulation of combustible materials on the surface of heat exchanger components, as this could otherwise trigger an air preheater fire. During ignition, no-load, and low-load conditions, the air preheater rotor must remain rotating; regular sootblowing should be performed to keep the component surfaces clean; closely monitor the temperatures of flue gas and air in the air preheater, and promptly investigate and eliminate any abnormal temperature readings. If secondary ignition occurs, ensure that the forced-draft fan, induced-draft fan, sootblower, and low-pressure water supply are all operating normally; the fire monitoring system must also be kept in working order. Pre- and Post-Operation Checks: 1. Inspect and thoroughly clean the upper part of the air preheater components, temporary walkways inside the flue duct, scrap metal, supports, and other debris. 2. Check whether the welds of the sootblower gun holder are firm and reliable; if necessary, take reinforcement measures to prevent the sootblower holder from falling off and getting stuck in the rotor. 3. Use a handle to rotate the rotor two full turns and verify that it rotates freely. 4. Check whether the high-pressure water and steam pipelines, valves, and steam drain lines are functioning properly; ensure that the pressure and superheat before the sootblower valve are within normal ranges. 5. Inspect the radial, circumferential, and axial sealing clearances and the bolts securing the sealing strips to ensure they are in good condition. 6. Check that the oil levels in the top and bottom bearings of the rotor and in the gearbox meet the required standards. 7. Verify that the inlet and outlet dampers of the air preheater are fully closed. 8. Inspect the fire monitoring equipment and confirm that the local control cabinet is operating normally. 9. Ensure that the rotor stall alarm device is functioning correctly. 10. Check that the air preheater gearbox and upper and lower bearings are operating without unusual noises. 11. Verify that the current drawn by the drive motor is within the normal range. 12. Confirm that the inlet and outlet temperatures of air and flue gas in the air preheater are within acceptable limits. Sootblowing of Heat Exchanger Components: 1. After the air preheater is running normally, perform sootblowing every 8 hours, strictly following the instructions provided with the sootblower. Ensure that the operating resistance of the air preheater remains within the design range. Increase the frequency of sootblowing before shutdown, during boiler startup, and during periods of low unit load. 2. To prevent condensation on the surface of heat exchanger components, perform steam sootblowing when the components are at higher temperatures. Therefore, sootblowing should be carried out only when the unit has reached a certain load level. 3. To ensure effective sootblowing, strictly prevent any external moisture from entering the air preheater. Pay attention to using superheated steam with adequate pressure and temperature to guarantee dry cleaning media. The steam temperature for sootblowing should be maintained between 120°C and 330°C, with a nozzle outlet pressure of 1.5 MPa. Using steam containing water can exacerbate corrosion of the heat exchanger components. 4. Ensure that condensate from the steam lines does not enter the sootblower. Thorough and effective drainage must be performed before sootblowing. Water in the steam can cause corrosion of the components, increase the adhesion and hardness of deposits on the surface of the heat exchanger components, making them difficult to remove through steam sootblowing, and intensify fouling and blockage. 5. If the cold-end temperature is found to be too low during sootblowing, take preventive measures in advance (such as activating the air heater or recirculating hot air) to raise the wall temperature of the cold-end components and ensure that the "combined cold-end temperature" of the air preheater is not less than the minimum recommended value (i.e., the cold-end flue gas temperature plus the air temperature should not be lower than 150°C). Heat Exchanger Component Cleaning: 1. During operation, if the resistance of the air preheater exceeds 35%, the unit should be shut down and cleaned with high-pressure water. High-pressure water cleaning of heat exchanger components is strictly prohibited when the unit is under load, as the sudden flushing action of high-pressure water can cause thermal shock, leading to fatal damage to the enamel and the component body itself. If necessary, cleaning should be carried out after the unit is shut down, with a maximum high-pressure water pressure of 15 MPa and the air heater activated. 2. When the operating resistance of the air preheater exceeds 25% of the design value, use low-pressure water for cleaning. Once low-pressure water cleaning is initiated, ensure thorough removal of any residue; otherwise, hard deposits will form on the component surfaces. The ideal temperature for the cleaning water is between 50°C and 60°C. Low-pressure water cleaning is typically performed at low rotational speeds, while the components are at a temperature about 35°C to 45°C above ambient temperature. Low-pressure water cleaning is more effective, and after cleaning, the components should be dried with hot air.