The height issue of carbon dioxide emission outlets?

The carbon dioxide emission stack on our unit is 180 meters tall.

It’s so tall; it must be a boiler chimney!

Have you seen a boiler chimney with this structure?

Why is there so much carbon dioxide that needs to be emitted? ? ?

Many chemical processing projects generate large amounts of CO2 emissions. For example, in coal gasification units, raw coal is ground into powder (or converted into coal slurry), which is then gasified in a gasifier to produce H2, CO, H2+CO syngas, and CO2. H2, CO, and syngas serve as raw materials for alcohol production, while the large amount of CO2 produced must be emitted. If CCS technology (carbon capture) can be applied on a large industrial scale, carbon dioxide emissions can be reduced.

Currently, addressing climate change and reducing greenhouse gas emissions falls under the responsibility of the Ministry of Ecology and Environment. Under the existing ecological and environmental standard system, carbon dioxide is not considered an air pollutant; moreover, the current standards for various pollutants do not set any requirements regarding carbon dioxide emission parameters such as emission concentration, emission rate, and emission height. Therefore, from the perspective of the ecological and environmental management system, there are no requirements regarding the emission height of carbon dioxide. And these days, the exhaust stacks typical of many large chemical plants that are involved in carbon dioxide emissions – such as those for low-temperature methanol washing waste gas and those for power station boilers – are quite tall. This is mainly due to the impact of other pollutants emitted from these stacks on the atmospheric environment, as well as industry practices; it’s just my personal opinion, for reference only!

This outlet is high. Our low-pressure outlet is at 80 meters. There is another hot potassium alkali outlet, with a temperature of 80-90 degrees, containing a large amount of water vapor, and a height of about 30 meters.

There was once a large-scale project in which the height of the exhaust stack was insufficient and the overall layout was inappropriate; as a result, the efficiency of the air separation unit, located in the downwind area throughout the year, failed to meet the design standards. It was only through a reevaluation of the design that it was discovered that the air on the upwind side of the air separation unit contained insufficient amounts of N2 and O2, while the CO2 level was too high.

It is estimated that the emission rates of NOx and SOx in flue gases or exhaust fumes, as well as their concentrations at the ground level, determine the required height of the exhaust stack; sometimes it is also necessary to examine the diffusion and ground-level concentrations of carbon monoxide.

This needs to be planned based on the nature of your industry, in conjunction with the emission standards for air pollutants specific to different industries. The specific design institute or the unit that prepares the environmental impact assessment for you will specify the minimum required height.