Effect of pressure on nitrogen production and air-nitrogen ratio of carbon molecular sieve

Carbon molecular sieve air separation nitrogen production technology is a technology that uses the difference in the adsorption rate of carbon molecular sieve to oxygen and nitrogen in the air to achieve nitrogen and oxygen separation through pressure swing adsorption (PSA) or vacuum pressure swing adsorption (VPSA) process. This technology has the advantages of low energy consumption, high degree of automation and simple operation, and has been widely used in chemical, electronic, food preservation and other fields.

In the process of CMS air separation nitrogen production, pressure is one of the key factors affecting nitrogen production and air-nitrogen ratio. Pressure not only affects the adsorption capacity and adsorption rate of the adsorbent, but also affects the flow state and mass transfer process of the gas in the adsorption bed. Therefore, studying the influence of pressure on CMS nitrogen production and air-nitrogen ratio is of great significance for optimizing process parameters and improving nitrogen production and purity.

2. Effect of pressure on nitrogen production

Studies have shown that within a certain pressure range, the nitrogen production of CMS increases with the increase of pressure. This is mainly because:

Increase in adsorption capacity: As pressure increases, the density of gas molecules increases, the number of gas molecules per unit volume increases, and the adsorption capacity of the adsorbent for gas also increases.

Accelerated adsorption rate: As pressure increases, the movement speed of gas molecules increases, the frequency of collisions with the adsorbent surface increases, and the adsorption rate increases.

Increased mass transfer driving force: As pressure increases, the gas partial pressure increases, the gas concentration difference inside and outside the adsorbent increases, and the mass transfer driving force increases, which is conducive to the diffusion of gas molecules into the adsorbent.

However, when the pressure exceeds a certain range, the increasing trend of nitrogen production will gradually slow down, or even decline. This is mainly because:

Adsorption heat effect: Excessive pressure will lead to aggravated adsorption heat effect, increased adsorbent temperature, and decreased adsorption capacity.

Increased bed pressure drop: Excessive pressure will lead to increased pressure drop of gas through the adsorption bed, and increased energy consumption.

Increased equipment cost: High-pressure operation requires higher equipment materials and sealing performance, and increased equipment cost.

3. The effect of pressure on air-nitrogen ratio

The air-nitrogen ratio refers to the ratio of the volume of air entering the adsorption tower to the volume of nitrogen produced per unit time. The air-nitrogen ratio is an important indicator to measure the efficiency of CMS air separation nitrogen production. The smaller the air-nitrogen ratio, the higher the nitrogen production efficiency.

Studies have shown that within a certain pressure range, the air-nitrogen ratio decreases with increasing pressure. This is mainly because:

Improved nitrogen purity: As pressure increases, CMS's adsorption capacity for oxygen increases, nitrogen purity increases, and the air-nitrogen ratio decreases.

Increased nitrogen production: As pressure increases, nitrogen production increases, and the air-nitrogen ratio decreases.

However, when the pressure exceeds a certain range, the downward trend of the air-nitrogen ratio will gradually slow down, or even increase. This is mainly because:

Oxygen adsorption saturation: Excessive pressure will cause CMS to adsorb oxygen to saturation, the nitrogen purity will be limited, and the air-nitrogen ratio will slow down.

Increased energy consumption: Excessive pressure will lead to increased energy consumption and reduced economic efficiency.