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Applicering av kolmolekylsikt vid konservering av livsmedel

Tid: 2021-02-26 Träffar: 16

    Now nitrogen is more and more widely used in food preservation, because nitrogen is a very inactive substance, Under normal temperature and pressure, most substances will not react with it. Using nitrogen to isolate oxygen to regulate the existing atmosphere of food can slow down the oxidation and stop the metabolism and respiration of food. At the same time, most microorganisms also lose their living environment.

    There are three existing nitrogen production methods, namely, cryogenic air separation, molecular sieve air separation and membrane air separation. The cryogenic air separation plant is suitable for large-scale industrial nitrogen production, with complex equipment, large floor area, high capital construction cost, large one-time investment, high operation cost and slow gas production. Although membrane air separation is suitable for small and medium-sized nitrogen users, it is similar to molecular sieve of the same specification The equipment price of air separation method is more than 15% higher than that of molecular sieve air separation method. The process flow of molecular sieve air separation method is simple, the degree of automation is high, the gas production is fast, and the energy consumption is low. Secondly, the purity of nitrogen can be adjusted according to the needs of users in a large range, with convenient operation and maintenance, low operation cost, and strong adaptability of the device.

    At present, nitrogen production by pressure swing adsorption (PSA) of kolmolekylsikt is based on clean compressed air as raw material and carbon molecular sieve as adsorbent. The principle of PSA is used to make the kolmolekylsikt full of micropores selectively adsorb gas molecules to obtain nitrogen. After the molecular sieve adsorption is saturated, the oxygen molecules in the holes of molecular sieve need to be discharged for the next work. When the oxygen molecules are discharged, the carbon will be discharged The pressure of molecular sieve layer is reduced from 0.3-0.6mpa to normal pressure after pressure equalization. The partial pressure of oxygen in the hole of carbon molecular sieve is greater than that of external oxygen. Oxygen flows outward from the hole, and the adsorbed oxygen molecules are released from the hole of molecular sieve.


    Although the existing nitrogen production system can provide nitrogen atmosphere for food preservation, when compressed air enters the adsorption tower with carbon molecular sieve distribution, the air flow impacts at high speed and the distribution is uneven. Carbon molecular sieve is easy to beat or even pulverize, which makes the adsorption effect quickly worse, the adsorption efficiency is not high, the service life of carbon molecular sieve is shortened, and the purity of nitrogen produced is also affected, which is the most important It is important to use nitrogen for food preservation, which is different from industry. It needs more pure nitrogen to protect food from anaerobic bacteria and dust pollution.

    Therefore, it is necessary to develop a pressure swing adsorption (PSA) carbon molecular sieve nitrogen system for food preservation, which can provide pure nitrogen and prolong the service life of carbon molecular sieve.