Problems and solutions in hydrogen peroxide desulfurization
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Since the first hydrogen peroxide-based desulfurization unit was built in China in 2012, over 100 such units have now been used for treating sulfuric acid exhaust gases. The desulfurization tower uses a air-sparged tower, which has low resistance but makes it difficult to meet the standards regarding acid mist in the exhaust gases ； Using power waves results in high resistance and high energy consumption ； Please ask Haiyou to talk about the problems encountered during the use of hydrogen peroxide for desulfurization and the solutions to them.
When the circulating liquid from the hydrogen peroxide tail washing tower is added to the circulation tank, the sulfuric acid changes color; moreover, an increased acidity in the circulating liquid of this tower tends to cause foaming, which results in higher pressure at the inlet of the tail washing tower.
This post was last edited by YoumingYouli on May 16, 2019, at 09:49. First issue: The diluted acid circulating in the tail washing tower is turbid; after being added to the circulation tank, the sulfuric acid also becomes turbid. There is a lot of acid sludge in the inlet pipe of the tail washing tower, which needs to be thoroughly cleaned. Do not add large amounts of diluted acid all at once； The second issue: Sulfuric acid exhaust contains insoluble gases such as N2 and O2. During thorough contact with the absorbent solution, these insoluble gases are surrounded by the absorbent solution, forming a gas-liquid interface; under the effect of high surface tension, spherical bubbles are created. A large number of bubbles rise rapidly to the surface of the circulation tank due to the density difference between gas and liquid, forming a layer of foam. This is particularly evident in desulfurization units that use tower spray irrigation when the system is restarted after shutdown; the more foam there is, the greater the surface tension, and the bubbles are less likely to burst. This leads to an increase in the foam layer on the surface of the circulation tank, resulting in an inaccurate liquid level and ultimately causing the absorption solution to overflow. First, pump out some of the absorbent solution to lower the liquid level in the circulation tank, and then reduce the density of the absorbent solution by adding water.
For all tail-suction processes, a humidifying device is required; otherwise, the acid mist cannot meet the specified standards
Is a tray tower better, or a packed tower?
A packed tower is used, with a demister installed at the top of the tower; this allows the acid mist concentration to be kept below 30 mg/m3, eliminating the need for an additional electrostatic demister； Using an air spray tower with a small diameter and high gas velocity, even with humidification, the acid mist may not meet the standards.
A packed tower is used, with a demister installed at the top of the tower; this allows the acid mist concentration to be kept below 30 mg/m3, eliminating the need for an additional electrostatic demister； Using an air spray tower with a small diameter and high gas velocity, even with humidification, the acid mist may not meet the standards.
For a system with a capacity of 500 kt/a, when the capacity is increased to 600 kt/a, a packed tower is used, equipped with a foam layer and wet electrostatic precipitators. The emission standards from the chimney are met, and there is no trailing exhaust plume visible at the chimney’s outlet. Considering that smelting flue gas may, under certain conditions, introduce high concentrations of sulfur dioxide, to ensure that emissions are within specified limits, it is planned to add an additional stage of sodium-alkali spraying after the packing tower.
I would like to ask: do you mean that when the circulating liquid from the hydrogen peroxide tail washing tower is added to the circulation tank, the sulfuric acid changes color – does it turn white? What’s the situation again?