Yellow phosphorus tail gas steam boiler

The yellow phosphorus tail gas steam boiler adopts a boiler structure that separates combustion and heat exchange, avoiding direct erosion of the boiler equipment by high-temperature flames. The tail gas from the yellow phosphorus electric furnace is collected by the three towers of the electric furnace for phosphorus collection and washed by the third stage water washing tower. After removing most of the dust impurities, fluorine, phosphorus, and sulfur, it is transported to the combustion chamber of the boiler for combustion. The high-temperature flue gas formed in the burner is about 1500 ℃; Blow in cold air from the distribution fan, dilute and cool the high-temperature flue gas to about 550 ℃, and then enter the boiler evaporator for heat exchange with the tubes; The evaporator body and steam drum form a steam generator through upper and lower circulation pipelines. Soft water absorbs heat in the evaporator body to generate a steam water mixture, which enters the steam collector through the upper circulation pipeline for steam water separation. The separated saturated steam is transported outward through the steam outlet of the steam drum for production use; The soft water that has not been vaporized returns to the evaporator body through the lower circulation pipe for further heat absorption and evaporation; After the heat of the high-temperature flue gas is released in the evaporator, the temperature drops to around 250 ℃ and is then extracted by the induced draft fan.

The principle of using yellow phosphorus tail gas to burn boilers to produce steam is similar to that of gas boilers. Boiler equipment is difficult to withstand the corrosion of yellow phosphorus tail gas during the combustion process, and its corrosion mechanism mainly includes the following two points:

1. After spraying water to collect phosphorus and simple gas washing, the yellow phosphorus tail gas can remove most of the elements such as fluorine, phosphorus, and phosphorus. However, there are still a small amount of sulfur and phosphorus that are difficult to remove. The acidic oxide gas generated after the combustion of these sulfur and phosphorus substances will cause high-temperature oxidation corrosion and hydrogen embrittlement to the boiler, and trace amounts of fluorine will cause equipment point corrosion and intergranular corrosion. The higher the combustion temperature in the furnace, the higher the concentration of atomic oxygen in the furnace, Converting more SO2 into SO3 will enhance the corrosion of the equipment. On the tail of the boiler flue and the heat exchange fin tube of the energy-saving device, when the flue gas temperature is below 220 ℃, acidic gases such as SO3 and P2O5 in the flue gas condense and form low-temperature acid dew point corrosion on the furnace wall.

2. On the other hand, some phosphorus containing particles in the exhaust gas undergo directional movement under the action of directional wind and wind speed in the furnace without complete combustion. They adhere to the heat exchange tube wall and continue to burn, generating low melting point phosphorus iron, iron carbonate, and sulfate, causing the oxide film protecting the tube wall to be damaged and subsequently corroded. Therefore, yellow phosphorus tail gas will cause very serious corrosion to gas equipment in a very short period of time during the combustion process, leading to equipment scrapping.