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Common problems and solutions of zeolite runner (zeolite molecular sieve runner)

The molecular sieve adsorption wheel system uses the continuous process of adsorption-desorption-concentration and incineration to process and purify VOCs waste gas. It has the advantages of wide application range, high safety and stable operation. However, in different practical applications, the composition of the exhaust gas is complex, and residual polymerization and smoldering of high-boiling VOCs are prone to occur.
 
 
  1. Residual polymerization of high boiling point VOCs
 
  When the exhaust gas treatment contains high-boiling VOCs, if the desorption heat is insufficient, the adsorbate is not completely desorbed, which will cause the adsorbate to accumulate and remain in the near adsorption short period, and polymerization will occur over time, which will block the adsorption position of the zeolite. The area adsorption efficiency is weakened. In order to completely desorb the high boiling point VOCs adsorbed in the zeolite, the following suggestions are given:
 
  (1) Install front-end high boiling point VOCs substance removal equipment
 
  In order to avoid the difficulty of desorption caused by the adsorption of high-boiling VOCs, a pre-filter cloth or activated carbon filter, and a demister or condenser can be installed before the exhaust gas enters the adsorption rotor to remove the high-boiling VOCs first.
 
  (2) Increase desorption heat capacity
 
  The first method is to increase the desorption temperature. It is recommended to control the temperature between 180-200℃, and the highest temperature should not exceed 220℃, so as to avoid excessive heat causing incomplete cooling and affecting the effect of the adsorption section; the other method is to increase the desorption regeneration air volume. Reduce the concentration ratio, so that a full desorption regeneration effect can be achieved.
 
  (3) Regular maintenance and cleaning with clean water
 
  Pay attention to the water quality when cleaning. If a large amount of calcium and magnesium plasma are contained in it, carbonates may be formed in the zeolite, blocking the honeycomb pores of the zeolite runner; and the chloroform in the water may occupy the adsorption position of the zeolite and hinder VOCs. The adsorption efficiency of zeolite, in addition to the trace heavy metal substances contained in the water will also poison zeolite. Therefore, it is recommended to use high-pressure nozzles to form the cleaning water into fine droplets, and use clean air in the cooling section of the system as the air flow carrier.
 
  (4) Regular high temperature desorption regeneration
 
  Regular high-temperature desorption treatment will effectively remove high-boiling VOCs, and at the same time, it can also achieve the effect of activating the zeolite runner. Generally, the desorption temperature is 300°C.
 
  2. Smoldering occurs
 
  Under 180-200℃ desorption conditions, if the system stops abnormally without air flow and no additional oxygen supply, the VOCs in the exhaust gas and the high-boiling substances polymerized on the runner will be combined with the zeolite in the runner. The oxygen remaining in the pores of the runner and the pores of the zeolite undergoes a catalytic reaction, forming an exotherm, causing smoldering, and destroying the structure of the zeolite. In order to prevent smoldering, it is recommended to use pure gas (such as nitrogen) as the protective gas when the system is abnormally shut down. At the same time, use water spray device as the best solution to prevent the smoldering phenomenon from continuing.