Waste heat recovery and utilization system of boiler flue gas
Because there are some design and installation defects in the early design and installation of the boiler, in the long-term operation of the later boiler, the ash accumulation, wear and tear in the boiler and the deviation of coal quality from the design value are the main factors affecting the boiler. The phenomenon that the exhaust gas temperature of the boiler exceeds the design value is widespread, which not only directly causes the boiler to operate. The decrease of efficiency leads to the waste of energy, and greatly affects the dust removal efficiency and service life of the dust collector, as well as the operation efficiency of the desulfurization and denitrification system.
At present, the traditional heat pipe and finned tube heat exchanger technologies are mainly faced with the following problems in the process of waste heat recovery from boiler flue gas in power plants:
1. Low-temperature corrosion caused by flue gas condensation: When the wall temperature of heat pipe heat exchanger is lower than the condensation acid dew point of sulfuric acid vapor, sulfur dioxide and sulfur trioxide gas in flue gas will condense on the wall of heat exchanger to form acid solution to cause equipment corrosion.
2. Abrasion and blockage of a large amount of fly ash in flue gas: The traditional heat exchanger can not timely judge the change of coal type and boiler load and adjust the wall temperature of heat exchanger in real time, resulting in blockage of ash on the wall of heat exchanger after dew or uneven flow rate of flue gas in heat exchanger due to partial blockage of ash. The formation of partial flue gas corridor causes rapid internal wear of heat exchangers.
At present, our company combines cryogenic economizer with phase change heat exchanger to design and produce a flue gas waste heat recovery system with independent intellectual property rights products, and thoroughly solves the problems of low temperature corrosion and wear through a new design concept. To ensure that the wall temperature of the heat exchange surface of the flue gas waste heat recovery system is always higher than the acid dew point of the flue gas at 5-15 C. Our company's waste heat recovery system relies on the advanced automatic control system and realizes the goal of adjustable wall temperature and controllable unattended on the basis of the on-site working conditions. Even when the load of the boiler body and the type of coal entering the boiler have changed greatly, the waste heat recovery system of our company ensures the safe and stable operation of the boiler body at the same time, reasonably lowers the exhaust gas temperature, and creates considerable economic benefits for the enterprise.