Molecular sieve dehydration
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Dear experts: Our factory’s gas dehydration unit is a facility capable of processing 1 million cubic meters of natural gas per day; it uses 4A molecular sieves, and the regeneration process involves counter-current regeneration using high-pressure dry gas (the process details are provided below). The problem we face is that heating for regeneration is difficult – according to the original design, it should take 6 hours to reach 204°C; however, Tower A requires 8 hours, while Tower B needs 12 hours. The amount of gas used for regeneration is 70,000 cubic meters per day, whereas the actual amount of gas processed is 780,000 cubic meters per day. We would appreciate your advice.
1. Check whether the natural gas valve has internal leakage. 2. Is the pressure difference in the dryer within the design range, and is there any crushing or caking of the desiccant? 3. Increase the supply of recycled gas.
Check the voltage of the regenerator, whether the wiring is correct, and whether there is a missing phase in the power supply.
This post was last edited by yfq4308 on 2010-10-15 22:28. Questions that need to be answered: 1. How long has your device been in operation? Did the above problem occur during the testing phase, or did it appear only after the system had been in operation for some time? 2. Are the molecular sieves imported or domestically produced? 3. Does your regenerative heater use electric heating, or heat transfer oil or steam? 4. What method is used in the front-end desulfurization and decarbonization system? 5. Raw gas components? Is there a large amount of heavy hydrocarbons, and is the pre-treatment operation stable? 6. How is the dehydrating effect? Is there any occurrence of unqualified dehydration? Possible reasons (guesses): 1. The purification process at the front end is not stable, allowing a large amount of impurities that should have been removed throughout the entire process to enter the molecular sieve, thereby causing poisoning of the molecular sieve and making regeneration difficult. There was once such a problem in the unit: large amounts of heavy hydrocarbon components entered the molecular sieve and were adsorbed, making regeneration difficult. 2. Is the heating power of the regenerator heater not sufficiently high during the design phase? It’s just a guess – we are not aware of the conditions under which it has been operating so far. 3. This phenomenon may also occur if there are issues with the quality of the molecular sieve. To make a judgment on specific issues, a large amount of information about the actual conditions on site is needed in order to arrive at a more scientific conclusion. What has been mentioned above are merely guesses for reference only. Meanwhile, it is hoped that if the original poster manages to solve this problem, they can share the solution with everyone, so as to facilitate mutual discussion and improvement.