What adsorbents does Steel Plant need
Time:2025-08-10
In the steel production, adsorbents are widely used, mainly for waste gas treatment and other processes. Adsorbents can effectively remove harmful substances and improve the cleanliness of the production environment. Below, we will make a detailed introduction to several commonly used adsorbents and their applications in steel production.
1、What is an adsorbent? Why is it so important in steel production?
Adsorbent is a solid material which can selectively aggregate specific substances (adsorbates) on its surface or pores through physical or chemical reactions. In the complex environment of high temperature, dust, and harmful gases in the steel industry, adsorbents are mainly used for:
* Purification and Separation: Removing impurities and harmful components from raw gas and liquid.
* Environmental production: Treat waste gas and wastewater generated during sintering, coking, ironmaking, and steelmaking processes to achieve standard emissions.
*Quality improvement: Remove harmful elements from the molten steel during the smelting process to improve the purity of the steel.
2、Types and application scenarios of adsorbents in the steel industry:
# Activated Carbon
Activated carbon is one of the most commonly used adsorbents in steel plant, with a developed pore structure and a huge specific surface area. It mainly relies on physical adsorption and can adsorb various harmful gases and impurities. In the treatment of steel plant exhaust gas, activated carbon is mainly used to adsorb harmful substances such as SO2 and CO2 in the flue gas, reduce the concentration of exhaust gas emissions, and meet environmental protection requirements.
The main purpose is to remove pollutants such as sulfur dioxide and heavy metals from flue gas, which is the core material for achieving ultra-low emissions.
# Activated alumina
Activated alumina is usually chosen as spherical, with high mechanical strength, good thermal stability, and extremely strong affinity for moisture. In the process of steel production, the main appliction are as follows:
*Gas drying: Used for deep drying of process gases such as compressed air, oxygen production systems, and blast furnace blowing to protect subsequent equipment from moisture corrosion.
*Fluoride removal: It is more widely used in the electrolytic aluminum industry, but it is also used in gas protection for certain special steel grades.
# Molecular sieve
Molecular sieves have a uniform microporous structure and are adsorbents with specific pore sizes that can selectively adsorb molecules based on their size. In steel plant, molecular sieve 13x are mainly used for gas separation and purification, such as separating oxygen, nitrogen, etc. from air. In addition, molecular sieves can also be used to remove impurities such as water and carbon dioxide, and improve gas quality.
*Deep drying and purification: Used for separating and purifying oxygen, nitrogen, hydrogen, CO gases, etc., removing trace amounts of water and CO2 from them.
*PSA oxygen/nitrogen production: used as the core adsorbent in pressure swing adsorption units, providing gas for steelmaking and blast furnace enrichment injection.
# Silica gel
Silca gel is an inorganic polymer material with strong adsorption properties. The moisture absorption capacity is slightly lower than molecular sieve zeolite, but silica gel has a cost advantage. In steel plant water treatment, silica gel is mainly used to remove harmful substances such as heavy metal ions and suspended solids in water, and improve water quality cleanliness. Meanwhile, silica gel can also be used for drying and moisture prevention, ensuring the normal operation of production equipment.
In summary, adsorbents play an important role in the production process of steel production, effectively removing harmful substances and improving the cleanliness of the production environment. Activated carbon, molecular sieve, activated alumina and silica gel are several commonly used adsorbents in steel production, each with their own advantages in different application scenarios. With the continuous improvement of environmental protection requirements, the application of adsorbents will become more widespread, providing strong support for the green development of steel mills.
Air adsorption dryers are familiar in the chemical industry, and their core components are adsorbents , such as activated alumina, molecular sieves, silica gel. They adsorb water and gas through a porous structure, and their performance affects the drying effect directly. As the adsorption regeneration cycle progresses, the adsorption capacity gradually decreases and needs to be replaced regularly to ensure stable system operation.
The replacement cycle is usually 3-5 years, but it needs to be adjusted based on the following factors:
1. Frequency of use: High frequency use will accelerate the saturation of the adsorbent, and the cycle needs to be shortened; Long term high load operation will accelerate the decline of adsorbent performance;
2. Environmental humidity: The higher the humidity of the inlet air, the greater the adsorption load and the corresponding decrease in lifespan; High temperature, high dust and other harsh environments may require early replacement.
3. Operating parameters: Abnormal pressure or increased dew point temperature may indicate adsorbent failure.
Meanwhile, during work, it is important to pay attention to the following matters:
1. Monitoring indicators: Regularly monitor the dew point temperature at the outlet, and if it continues to exceed the standard, check the status of the adsorbent.
2. Replacement operation: Thoroughly clean the adsorption tower during replacement to avoid mixing of new and old adsorbents; The filling should be evenly compacted to prevent air flow short circuits.
3. Selection matching: The new adsorbent should be consistent with the prototype number to ensure that the porosity and mechanical strength meet the requirements.
4. Regeneration inspection: After replacement, verify the regeneration effect and confirm that the heating temperature and cooling time are normal.
So how to choose the right adsorbent for an adsorption dryer?
1) Molecular sieve: It is a crystal structure with uniform pore size and strong adsorption ability for water molecules, especially suitable for precision industrial scenarios with dew point below -60 ℃. However, due to its low strength, it is easy to be pulverization under high-intensity compressed air impact, so it can only be used in small quantities in traditional twin tower adsorption dryers.
2) Activated alumina: It is a high-strength adsorbent and the most widely used adsorbent in adsorption dryers currently. It can withstand the high-pressure impact of compressed air without powdering. Excellent performance in moderate humidity environments, suitable for places with dew point below -40 ℃, with a regeneration temperature 30-50 ℃ lower than molecular sieves.
3) Silica gel adsorbent: It’s getting less and less in compressed air drying. It is only suitable for drying at room temperature and is used in pressure dew point environments of -20 ℃.
In terms of drying performance, molecular sieves are much stronger than activated alumina, but the replacement cost is higher. Therefore, before choosing which adsorbent, it is necessary to understand the user's requirements or expectations for dew point, so as to choose the best solution that can meet the user's requirements and reduce the cost of use.
