Which molecular sieve of 3A and 4A has the smallest pore size?
When purchasing molecular sieves, you do not specifically say which molecular sieve is better, only which molecular sieve is more suitable. The main function of molecular sieve is to sieve a substance molecule through the pore size of the molecular sieve's own crystal structure. When meeting the technical requirements of water removal, is it better to use 3A molecular sieve or 4A molecular sieve? First of all, this problem still needs to be specifically distinguished from the substance to be dehydrated. First, the size of the molecular diameter of the moisture (dry) needs to be removed. If the dynamic molecular diameter of the substance to be dehydrated (dry) is greater than 3nm and less than 4nm, then, If we want to get rid of water from this substance, we can only use 3A molecular sieve, because if we use 4A molecular sieve, it will not only absorb the water in the substance, but also absorb the substance that needs to be dehydrated. This is the first case, and there is another The situation is that if the dynamic diameter of the material that needs to be dehydrated (dried) is greater than 4A, then 4A molecular sieves are generally used, because 4A molecular sieves have a stronger ability to absorb moisture than 3A. If both 3A molecular sieve and 4A molecular sieve can be used to remove water, which molecular sieve should we use? In this case, we generally use 4A molecular sieve, because the water absorption of 4A molecular sieve is more than 22%, and the water absorption capacity of 3A is more than 21%. Generally speaking, the water absorption capacity of 4A molecular sieve is stronger than that of 3A molecular sieve. That is, the price of 4A molecular sieve is cheaper than that of 3A molecular sieve.
The reason why activated carbon is used as a regeneration Material
Activated carbon itself has heat resistance, acid and alkali resistance, oxidation resistance, and also has a certain strength. Therefore, in addition to ensuring the above properties of activated carbon, the regeneration treatment should also make the adsorption performance of activated carbon reach 90% of the original carbon. Above, at the same time, the mechanical abrasion and breakage of the carbon during the regeneration process are reduced as much as possible, so that the regeneration yield can reach more than 90%. In addition, the economics of the regeneration process must be considered. Taking the widely used heating regeneration method as an example, it is reported that the regeneration is only beneficial when the amount of activated carbon used per day is about 100kg or more. Therefore, the economic performance of regeneration is also an important factor for investigating activated carbon regeneration. The adsorption of activated carbon can generally be divided into reversible adsorption (also called physical adsorption) and irreversible adsorption (also called chemical adsorption) according to the adsorption mechanism. In practical applications, the two adsorptions are often mixed alternately. Generally, the reversible adsorption process occurs in gas phase solvent recovery, deodorization, air purification, etc., while the irreversible adsorption process is common in the liquid phase adsorption of wastewater treatment. The regeneration treatment method for reversible adsorption is mainly to pass heating steam above 120°C to remove the adsorbed substances and restore the adsorption performance of activated carbon. However, due to the different vapor pressures and boiling points of the adsorbed substances, their effective adsorption capacity will change, and the regeneration conditions should also change.
Common faults and treatment methods of PSA nitrogen generator
1. During operation, the large pressure displayed on the meter head can not reach the set value. It is caused by the leakage device. Perform a comprehensive leak detection on the gas circuit, especially the drying room and the battery. 2. Check whether the battery is leaking or broken 3. There is noise during the operation of the instrument It is the solenoid valve sound: use a 14 wrench to properly adjust the tightness of the nut on the solenoid valve, not too tight; if not, you need to disassemble the solenoid valve to clean the interior (the sound is mainly due to impurities in the solenoid valve internal organs), and return it after cleaning. No, it must be replaced with a new one. Four, there is gas output when starting up When the pressure rises just after the start-up, you must press the red delay switch on the front, and then the output pressure will be released from the output and wait for 10 minutes before it can be used. The above is the most common troubleshooting of PSA nitrogen generator.
Industrial activated carbons covering fields and applications
1 Functional activated carbon activated carbons Activated carbon is an important functional material for national economic development and national defense construction. Activated carbon can be used for gas phase adsorption, liquid phase adsorption, electronic materials, medical treatment and many other aspects, and can be used as a catalyst and catalyst carrier. In recent years, with the rapid development of environmental protection, new energy and other industries, the market demand for functional activated carbon has surged. 2 Activated carbon modification Industrial development has increased the requirements for the adsorption capacity and catalytic activity of activated carbon. Conventional activated carbon can no longer meet the special requirements of various fields, and super activated carbon has emerged as the times require. Super activated carbon has a huge specific surface area and excellent adsorption performance, so it is widely used in fuel gas adsorption and storage, gas separation, catalyst carrier, electrode material of super capacitor and so on. In many applications, special activated carbon has also appeared, such as nickel-coated activated carbon suitable for removing alkyl sulfides in gas or exhaust gas, and special activated carbon for citric acid. Although the advantages of super activated carbon are obvious, the application of shortcomings is insufficiently studied, especially in the process of preparation and use, there are still some shortcomings that need to be further studied and improved. Activated carbon modification is to adjust its adsorption performance, adsorption capacity, catalytic activity and other properties to meet specific working conditions and application conditions. The modification of the adsorption performance of activated carbon is currently mainly focused on two aspects. One is to develop activated carbon with special properties, such as activated carbon fiber and wood activated carbon. The other is to modify the activated carbon to adjust the pore structure of activated carbon to improve the specific adsorption properties. Absorption capacity or desorption capacity. Activated carbon fiber (ACF) is the third-generation activated carbon product. It can be made into products of any shape, which can be decolorized and deodorized. It is suitable for solvent recovery devices, water purifiers, ozone filters, anti-virus masks, medical bandages, cigarette filters, Precious metal recovery equipment, etc. ACF is mainly used to treat micro-polluted raw water and low-concentration wastewater. One of the main reasons limiting its wide application is the high price.
The effect of industrial activated carbons on the environment
Until the 21st century, the application fields of activated carbons have been further expanded. Activated carbon is also involved in many high-tech fields such as environmental protection, energy and catalysts, gas storage, chemical separation, and biological organisms. Among them, the treatment and purification of industrial waste gas by activated carbon, including the removal of formaldehyde gas, is mainly dependent on its gas phase adsorption application, and activated carbon is dependent on it for pharmaceutical and chemical wastewater, precious metal recovery, and the most basic water treatment. The application of liquid phase adsorption is precisely because of the unique characteristics of activated carbon, so it is always indispensable when treating waste gas and wastewater. Nowadays, the development of activated carbon is becoming more and more diversified, and when dealing with different pollution, scientists have also developed different types of activated carbon to deal with. Targeted development of activated carbon with special adsorption properties has also become a top priority. It is hoped that one day activated carbon can better improve the environment and return the environment to its origin.
Quickly understand the classification of activated carbon
Activated carbon is a kind of black porous solid carbon, which is produced by pulverizing and shaping coal or carbonizing and activating uniform coal particles. The main component is carbon, and contains a small amount of oxygen, hydrogen, sulfur, nitrogen, chlorine and other elements. The specific surface area of ordinary activated carbon is between 500 and 1700 m2/g. It has strong adsorption performance and is an industrial adsorbent with a wide range of uses. Activated carbon is a traditional and modern man-made material, also known as carbon molecular sieve. Classification: According to the different sources of raw materials, manufacturing methods, appearance and shape, and application occasions, there are many types of environmentally friendly activated carbon. Up to now, there are no measurable statistical materials, and there are about thousands of varieties. According to the source of raw materials: 1. Wooden activated carbon; 2. Animal bones, blood charcoal; 3. Mineral raw material activated carbon; 4. Other raw material activated carbon; 5. Regenerated activated carbon. According to the manufacturing method: 1. Chemical activated carbon (chemical carbon); 2. Physical activated carbon; 3. Chemical-physical or physical-chemical activated carbon. According to appearance shape: 1. Powdered activated carbon; 2. Granular activated carbon; 3. Unshaped granular activated carbon; 4. Cylindrical activated carbon; 5. Spherical activated carbon; 6. Activated carbon of other shapes. According to the aperture: Macropore radius>20 000nm; transition pore radius 150-20000nm; micropore radius<150nm The surface area of activated carbon is mainly provided by micropores. Classified by material: Coconut shell activated carbon; nut shell activated carbon (including apricot shell activated carbon, fruit core shell activated carbon, walnut shell activated carbon); wooden activated carbon; coal-based activated carbon.