Seeking expert assistance in calculating the process parameters for using secondary nozzles and tower-based spray systems to absorb SO2 and H2SO4 from exhaust gases
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Hello, experts! I’m a beginner in chemical engineering design, and I’ve recently come across a project that involves designing an exhaust gas absorption unit. The inlet air volume is 20,000 m3/h, with a SO2 concentration of 900–1700 mg/m3, a H2SO4 concentration of 40–60 g/m3, and a temperature of ≤65°C. The required concentrations after treatment are ≤400 mg/m3 for SO2 and ≤40 mg/m3 for H2SO4 ； The absorbing agent is an NaOH solution with a concentration of 8% to 10% ； The absorption tower is equipped with 2 stages of turbulent flow nozzles and 1 stage of empty-tower spray, sharing 1 circulation pump. Please ask an expert to help calculate the process parameters!
This kind of problem involves two aspects: (1) mass conservation, which is the most fundamental principle; from this, the flow rate of NaOH required can be determined. Liquid is added in the upper section, while circulating spray occurs in the lower section. (2) Mass transfer calculation to determine the required height of the absorption tower. However, this is a case of acid-base neutralization and absorption; it doesn’t require anything large – only gas-liquid contact needs to be taken into consideration.
For chemical absorption, this treatment efficiency is already quite low; as long as the gas velocity in the empty tower is properly considered, along with the height of the nozzles and the spraying conditions, there is no need to consider anything else.
For SO2, the required absorption efficiency is relatively low, but the absorption efficiency for sulfuric acid is still quite high. Also, how should I choose between these liquid and gas forms? Is the liquid-to-gas ratio different for each nozzle?
I’m not sure about the liquid-to-gas ratio right now. . .
As a beginner in chemical engineering design, it’s impossible to carry out such process calculations. Either find an existing process as a reference or use software to do some calculations, but in most cases the results will be incorrect.
It’s just that there’s no existing technical reference available, sigh,,,