Project Introduction: The deep flue gas cooler, also known as a low-temperature economizer, flue gas waste heat utilization device, flue gas waste heat recovery device, or simply a flue gas cooler, recovers the waste heat from flue gas by heating a working medium such as water. This recovered waste heat can be used for: heating condensate; heating hot network water for heating purposes, and can also serve as a heat source for air conditioning systems; heating desulfurized low-temperature flue gas; as a heat source for an air heater, heating the boiler inlet air. By installing a deep flue gas cooler before the electrostatic precipitator, the temperature of the flue gas entering the precipitator can be reduced, which can decrease the volumetric flow rate of the flue gas, lower its velocity, and at the same time reduce the specific resistance of fly ash, thereby greatly improving the dust removal efficiency of the precipitator. Theoretical and demonstration projects have shown that this system can effectively avoid the synergistic effects of low-temperature corrosion and ash accumulation wear, ensure the long-term safe operation of the equipment, and can increase the efficiency of power plants by 0.5 to 1.2%. The efficiency of waste heat utilization exceeds 50%, saving standard coal consumption by 1.5 to 4g/kWh, significantly reducing the emissions of gaseous pollutants such as dust, SO2, NOX, and CO2, as well as the cooling water required for desulfurization. Currently, this technology has been applied in the retrofitting of 36 sets of circulating fluidized bed and pulverized coal generating units with capacities of 300MW, 600MW, and 1000MW, exceeding 50 contracts. Additionally, this technology can be used in any industrial process with combustion and smoke generation, contributing to energy conservation and emission reduction, making it suitable for widespread promotion. Key advantages of the technology include: 5 invention patents, 8 utility model patents, and 3 software copyright registrations. This patent portfolio is centered around a unique waste heat recovery system, which has invented patented technologies such as the deep flue gas cooler system and structural design methods. Its advancement lies in: achieving a new type of system, uniform flow, enhanced heat transfer, Heat exchange structure and system integration key technology innovation, waste heat temperature can be reduced to about 85-100°C, which allows the metal wall temperature to be below the dew point of sulfuric acid, deeply recovering flue gas waste heat. This solves the technical difficulties in synergistic action and prevention and control of waste heat recovery systems, heat exchange structures, as well as ash accumulation, wear, and low-temperature corrosion. The patented product has won the 2011 Shandong Province Excellent Energy Saving Achievement Award and the 2012 Seventh Civilian Enterprise Innovation Achievement Gold Award. The appraisal organized by the National Electric Power Planning and Design General Institute of Experts believes that: '...for the first time, it proposes...and other major technological innovations, and the design technical scheme has reached a leading level in China.' Xi'an Thermal Power Research Institute Co., Ltd. and other units have conducted actual operation energy efficiency tests on the products of 300MW unit of Huaneng Group Ningxia Daba Hydropower Plant and 1000MW unit of Datang Group Chaozhou Power Plant, which implement this patent group. The test results show that under rated load, The thermal efficiency of the steam turbine has decreased by 40.3 and 69.1 kJ/kWh, respectively, while the coal consumption rate for power generation has been reduced by 1.425 and 2.35 g/kWh, respectively. This offers comprehensive advantages in energy saving and emission reduction. The entire project investment can generally be recovered within 2-3 years, making it suitable for contract energy management. Development prospects and significance: The innovative technology proposed by the patent group of new waste heat recovery systems and devices is unique and advanced, leading both domestically and internationally. Since 2007, based on the patent ideas, 300, 350, 600, and 1000 MW thermal power units, as well as cement kilns of 2500, 3200, 4500, 5000, and 6000 t/d, glass kilns of 300, 500, and 900 t/d, ferroalloy waste heat boilers, polysilicon purification waste incineration waste heat boilers, and other systems have been designed and developed. The company has developed six major series of 26 types of flue gas waste heat recovery devices and products, including four models that fill domestic gaps, with overall performance superior to imported foreign products. Operational tests have shown that the deep cooler for thermal power plant flue gas products are reliable in operation, capable of simultaneously achieving dust removal, desulfurization enhancement, saving water resources, saving coal resources, and other multiple energy conservation and emission reduction advantages. The product market share exceeds 60%.