The mechanism of action of the desulfurizer and why the sulfur is reduced

Mechanism of action of activated carbon desulfurizer.

Activated carbon desulfurizer is one of the earliest dry desulfurizers used, and has been used for more than 70 years. The earlier activated carbon desulfurization technology equipment was huge, and the regeneration and sulfur ** processes were more complicated, and the operation was troublesome. In the 50s of the 20th century, it was gradually replaced by wet processing.

In recent years, due to the improvement and simplification of the regeneration method, and the development of activated carbon desulfurizer for fine desulfurization and normal temperature fine desulfurization technology, there are many small and medium-sized synthetic ammonia plants, urea plants, and hydrangol production plants using activated carbon desulfurizer dry removal of raw gas and part of the organic sulfur. This method has the advantages of large sulfur capacity, strong adaptability, low operating temperature, renewable and repeated use and sulfur, and the activated carbon desulfurizer is relatively cheap. However, activated carbon desulfurizers are limited to aerobic conditions, and the sulfur absorption capacity is very low in the absence of oxygen.

In terms of water resistance, activated carbon desulfurizers are superior to iron oxide desulfurizers.

The desulfurization mechanism of activated carbon is to use the catalytic action of the active groups on the surface of activated carbon to accelerate the following reactions of H2S and O2 in the gas

2h2s+ o2 →2h2o+2s δh=

The reaction of H2S and O2 on the surface of activated carbon is actually carried out in two steps, first is the adsorption of oxygen on the surface of the activated carbon to form the surface oxide of the active center, and then the H2S molecules in the gas react with the chemoadsorbed oxygen, and the resulting sulfur is deposited in the micropores of the activated carbon ash. In order to accelerate the reaction and improve the desulfurization effect, the actual ratio of O2 H2S should be greater than the theoretical value, and the ratio should be greater than 3.

The activated carbon desulfurizer may introduce active metals such as copper, alkali metals, alkaline earth metals, etc., by impregnation method to modify and improve its catalytic activity. The activated carbon crude desulfurizer can treat a higher content of sulfur, but the export gas still contains 20 30?g g of sulfur.

Low airspeed, large reload, and frequent regeneration. For example, a small ammonia plant purifies semi-aqueous gas with a sulfur (H2S) content of g m3 under the operating condition of atmospheric pressure h-1, and the sulfur can be removed to 54mg m3Each ton of ammonia consumes 62kg of activated carbon, ammonia and steam, and the regeneration cycle is 26 days.

The sulfur capacity of activated carbon refined desulfurizer is 4 6 times that of activated carbon crude desulfurizer. T103 type is a special fine desulfurizer for food-grade carbon dioxide, which also has a certain sulfur capacity for organic sulfur and can be used in 60 80.

The calculation shows that the equilibrium constant of H2S oxidation on activated carbon desulfurizer is much larger than that of zinc oxide desulfurizer at 30, while the equilibrium constant of H2S is about 10-17 lower from Table 5-25. This is also confirmed by the kinetic characteristics of the T101 activated carbon desulfurizer. It can be clearly seen from Table 5-26 that the working sulfur capacity of the original particle size of the activated carbon refined desulfurizer, which represents the internal diffusion during industrial production, is 3 times higher than that of zinc oxide desulfurizer, and its penetration airspeed is 2 times higher.

The sulfur capacity and accuracy of the desulfurizer are better than those of zinc oxide at room temperature, which will be reduced because the sulfur will precipitate with many metal ions.

Sulfur precipitates with many metal ions.

Flue gas desulfurization refers to the removal of sulfides from flue gas.

Flue gas desulfurization is generally divided into wet and dry desulfurization, semi-dry desulfurization, and now the more commonly used flue gas desulfurization method is SDS dry desulfurization, the main process is to send the activated calcium desulfurizer into the silo for temporary storage, and then in the lower part of the storage silo variable control feeder, combined with the change of flue gas volume to output an appropriate amount of active calcium desulfurizer, through the powder fan to the desulfurization reactor, so that the flue gas energy speed mixed with its entering, reaction to remove the sulfide and other components in the flue gas.

1. SDS dry desulfurization.

The main purpose of SDS dry desulfurization is to decompose the exhaust gas into sodium carbonate through reaction, and after the sodium carbonate is highly mixed with the flue gas, sodium sulfate and other sodium salts are generated, so as to achieve the flue gas emission standard and reduce environmental pollution.

Advantages of SDS dry desulfurization:

1.SDS dry desulfurization efficiency reaches more than 95% and can maintain continuous discharge;

2.SDS dry desulfurization equipment occupies a small area, has small site restrictions, low power consumption, low fault, and prolongs the life of the equipment;

3.SDS dry desulfurization systems have low temperatures, which are more energy-efficient and convenient than those processes that require high temperatures.

4.SDS dry desulfurization system operates in full dry mode, without wastewater treatment and discharge problems, no chimney tailing, and no flue gas whitening treatment.

2. Limestone - Shichang patting paste wet flue gas desulfurization process:

Limestone - gypsum wet flue gas desulfurization process principle This method is to grind limestone (lime) into fine powder, prepare into slurry, flue gas and limestone slurry flow down in the absorption tower, the SO2 in the smoke and limestone chemical reaction to generate calcium sulfite and calcium sulfate, in the bottom tank of the absorption tower into a large amount of air, calcium sulfite oxidation into calcium sulfate, crystallization separation of the by-product gypsum.

Limestone-gypsum wet desulfurization technology is mature, high desulfurization efficiency, large unit capacity, low operating cost and easy by-product desulfurization process.

Desulfurization refers to the fixation of the sulfur element in coal into a solid by calcium-based and other methods. The function of desulfurization is to prevent the formation of sulfur dioxide during coal combustion, and reduce the emission of gas that is delayed and harmful.

At present, there are dozens of types of flue gas desulfurization technologies, which can be divided into three types of desulfurization processes: wet, semi-dry and dry according to the dry and wet forms of desulfurization process and desulfurization products. According to the desulfurization method, it can be generally divided into three categories: pre-combustion desulfurization, combustion desulfurization and post-combustion desulfurization.

Special properties of sedimentation sulfur: it is decomposed by hydrochloric acid after the reaction of refined sulfur and calcined lime.

Physical. Sulfur element is commonly known as sulfur, and it is a light yellow solid in normal state, easily soluble in CS, insoluble in water, and slightly soluble in alcohol. The element sulphur is usually found in nature as a sulphide compound.

Sulfates or elemental forms are present. Sulfur is one of the essential mineral nutrients for plant growth, and it is a medium nutrient element.

Solubility. Sulfur is insoluble in water but soluble in carbon disulfide. Poor thermal and electrical conductivity.

It is crunchy and insoluble in water. Amorphous sulphur is mainly elastic sulphur, which is obtained by the rapid dumping of molten sulphur into ice water. Unstable and can be converted to crystalline sulfur.

Crystalline sulfur can be dissolved in organic solvents such as carbon disulfide (while elastic sulfur can only be partially dissolved) and carbon tetrachloride.

Toluene and benzene. In addition to 0 valence, common valence.

There are 3 kinds, which are -2 (hydrogen sulfide.

4 (Sodium sulfite.)

and +6 (sulfuric acid) valence; +2 valence (formaldehyde sodium bisulfite) is uncommon.

The above content reference: Encyclopedia - sulfur.

1. Slurry density.

2. Pulp supply.

3. Inlet SO2 concentration.

4. Oxygen supply.

5. The opening of the guide vane of the booster fan.

6. Slurry atomization spray.

7. Limestone quality.

Content 9Air leakage rate of air preheater.

There are many reasons for low desulfurization efficiency, to name a few:

1. The sulfur content of the coal used is higher than that of the design coal.

2. The actual flue gas volume is greater than the design flue gas volume.

3. The design of the desulfurization tower itself

The liquid-gas ratio is lower; The flow rate of the circulating pump is smaller; The air volume of the oxidation fan is smaller;

4. Operation problems: there is more dust in the desulfurization tower; The chloride concentration of the slurry is high; The density of the slurry is higher. Wait a minute.

Hello, glad to answer for you. "Desulfurization generally refers to the removal of sulfur from fuel before combustion and the desulfurization process before flue gas discharge. It is one of the important technical measures for the prevention and control of air pollution. There are generally three desulfurization methods: pre-combustion, combustion and post-combustion desulfurization. ”