Flue Gas Whitening for the Treatment of White Plumes in Industrial Flue Gas Emission Processes

Flue Gas Whitening for the Treatment of White Plumes in Industrial Flue Gas Emission Processes

Flue gas usually contains a large amount of water vapor and a small amount of sulfur dioxide, nitrogen oxides and other pollutants. When the high temperature, high humidity flue gas from the chimney discharge, and the lower temperature of the ambient air contact, water vapor quickly cooled and condensed into small water droplets, these small water droplets on the light to produce scattering and refraction, so that the flue gas appears to be white, the formation of white plume.

In winter or cold regions with low ambient temperatures, this phenomenon will be more pronounced. In addition, when the operating load of boilers and other equipment changes, inadequate combustion or desulfurization and denitrification process operation is unstable, it may also lead to an increase in the water vapor content of the flue gas, which in turn exacerbates the phenomenon of white smoke plume.

Hazards

Visual pollution: white plume will cause adverse impact on the surrounding environmental landscape, especially in the urban periphery or densely populated areas, the emission of a large number of white plume will give people the intuitive impression of serious pollution, affecting the city's image and people's visual perception.

Environmental impact: the water vapor in the white plume condenses to form small water droplets may adsorb pollutants in the flue gas, such as sulfur dioxide, heavy metals, etc., these pollutants with the water droplets settling to the ground, the soil, water and other environmental elements will cause pollution, affecting the ecological balance.

Corrosion of equipment: water vapor in flue gas, if condensed on the surface of chimney or other equipment, will form acid with acid gas in flue gas (such as sulfur dioxide, sulfur trioxide, etc.), which will corrode the equipment, shorten the service life of the equipment, and increase the maintenance cost.

Main technical methods

Condensation method: By lowering the temperature of the flue gas, the water vapor in it condenses into liquid water and is removed. Generally use equipment such as coolers, using circulating cooling water or other cooling media and flue gas heat exchange, so that the temperature of the flue gas is reduced to below the dew point temperature, water vapor condenses into water droplets and then discharged through the drainage system. This method can effectively remove most of the water vapor in the flue gas and reduce the production of white plume.

Reheating method: the low-temperature flue gas after desulfurization is heated through heat exchangers or burners and other equipment to increase the temperature of the flue gas, so that it exceeds the saturation temperature, so that the water vapor in the flue gas is in a state of superheat, and it is not easy to condense into small droplets, so as to achieve the purpose of eliminating the white smoke plume. Common reheat methods include gas reheat, steam reheat and heat medium reheat.

Condensation and reheat combined method: first use the condensation method to remove part of the water vapor in the flue gas, reduce the humidity of the flue gas, and then use the reheat method to raise the flue gas temperature to the appropriate range, further eliminating the white plume. This method combines the advantages of condensation and reheat method, which can solve the problem of white plume elimination more effectively, and at the same time, to a certain extent, it can also recycle part of the heat in the flue gas, so as to improve the efficiency of energy utilization.

Application Fields

Thermal power industry: The boilers of coal-fired and gas-fired thermal power plants produce a large amount of high-temperature and high humidity flue gas during the combustion process, which is one of the main application fields of flue gas whitening technology. Through the implementation of flue gas whitening measures, it can reduce the impact of white plume on the surrounding environment of the power plant, and at the same time help to improve the environmental image of the power plant.

Iron and steel metallurgy industry: The sintering machine, blast furnace, converter and other production equipment in the iron and steel plant will emit flue gas containing a large amount of water vapor and pollutants during the operation process, the use of flue gas abatement technology can effectively manage the white plume, reduce the pollution of the surrounding air environment and improve the air quality in the plant and the surrounding area.

Chemical industry: Some reaction devices and boilers in the chemical production process will also produce flue gas that needs to be treated, such as catalytic cracking devices in petrochemical enterprises and gas-making furnaces in chemical fertilizer plants. The application of flue gas abatement technology in the chemical industry helps to realize clean production and reduce the impact on the environment.