How do you deal with low-temperature exhaust gas during methanol washing when there is a lack of gas supply?
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Could the experienced colleagues please share their insights on how to deal with the damage caused by low-temperature exhaust gases to the subsequent pipelines during methanol regeneration, when the process air supply for methanol washing is suddenly interrupted? This post was last edited by z880347730 on 2009-4-11 11:22]
OP, is that Lind’s technique? In the Linde process that I am currently working with, there is a temperature interlock at the exhaust outlet of the feed gas pre-cooler; if the temperature drops below the set lower limit by two degrees, the valve will close automatically, thereby preventing the harmful effects of cold exhaust gas on the subsequent sections of the pipeline.
The process load keeps decreasing during parking~! The temperature of the exhaust gases is continuing to rise~! In the event of an emergency shutdown, the low-temperature interlock mechanism will take effect without affecting the pipelines downstream. During the regeneration process, the liquid level in the chillers in the cold zone is continuously lowered to maintain a certain temperature there; it is essential to prevent heat from the hot zone from affecting the cold zone
I’m stunned; I also have high methanol levels. I’m not familiar with that process you mentioned – it seems like my skills in this area aren’t good enough
What LZ said is a sudden interruption in the supply of process air; the temperature of the exhaust gases is very low in the short term, and as mentioned by someone on floor 3, the temperature gradually rises afterward. In the short term, this has little impact on the materials used
The design temperature for the material of the pipeline carrying exhaust gas out of the shift gas cooler is around –20°C. When the process gas supply is interrupted or the system is shut down, low-temperature methanol washing needs to be carried out for regeneration; during this process, the exhaust gas (at a temperature of –50 to –60°C) is reheated by the shift gas cooler before being released. If there is no stream available for heat exchange with the shift gas cooler, the temperature of the exhaust gas pipeline at the outlet of the cooler will drop below the designed value. The nitrogen filling pipeline during driving can be moved in front of the shift gas cooler; once the process gas supply to the current system is interrupted, the nitrogen filling valve can be opened. This helps to maintain the pressure required for methanol regeneration and, at the same time, removes the heat from the exhaust gases, thereby keeping the temperature in the exhaust pipes above the designed value.
Can’t we use the same material for the exhaust pipelines entering and leaving the heat exchanger?
Low-temperature materials are quite expensive! Hehe, normally normal-temperature materials are used!
We do not have the necessary conditions to modify the nitrogen filling pipeline of Tower T1 to lead it ahead of the raw gas heat exchanger; therefore, after each sudden interruption in the supply of raw gas, we open the bypass valve of Tower T6 (the exhaust gas washing tower) to allow the exhaust gas to be discharged via a bypass, bypassing the interior of Tower T6, thereby reducing damage to the equipment at normal temperatures!
So the bypass here is also designed for normal temperature conditions! So I’m afraid that taking a detour could also cause damage to it!