Abnormal temperature in the second feed gas heat exchanger of the liquid nitrogen quench tank
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The liquid nitrogen washing system in our company is a Zhongtai Technology cryogenic tank. Recently, the temperature at the hot side of the second feed gas heat exchanger has dropped abnormally, from -100°C to -135°C. As a result, the temperature of the nitrogen used for washing in the nitrogen washing tower, as well as that of the feed gas, increased slightly. Adjustments made through the fuel gas pipeline were ineffective, indicating that the second feed gas heat exchanger was no longer functioning properly; the cooling capacity could not be utilized to cool the medium-pressure nitrogen and feed gas inside the cryogenic tank, nor could it be transferred to the syngas exiting the heat exchanger. Adjustments to the flow rates of the raw nitrogen and the washing nitrogen also proved ineffective. Finally, by rapidly increasing the amount of nitrogen used for washing, we raised the temperature of the feed gas entering the washing tower to -171°C, at which point the temperature trend reversed: the temperature at the hot side of the second feed gas heat exchanger rose rapidly, while the temperatures of both the feed gas and the washing nitrogen dropped rapidly, returning to normal levels. However, the operating conditions cannot be maintained; the temperature at the hot side of the second feed gas heat exchanger will continue to decline. Overall, there are issues with the heat exchange performance of the second feed gas heat exchanger, while no significant changes occurred in the various parameters of the cold box during this period. I was wondering if anyone else has encountered a similar situation?
The specific process is not clear; it is recommended to provide a diagram of the previous process to facilitate discussion. It is recommended to start with an analysis of the material purity to check for issues such as cooler leaks, for reference.
To identify an excess of cooling capacity, it is first necessary to rule out any changes in the composition of the feed gas (such as carbon monoxide and methane). By reducing the flow rate of crude nitrogen, less cooling capacity is generated; meanwhile, the fuel gas flow rate should be adjusted accordingly to ensure that there is no increase in trace substances.
It is estimated that the gas composition has changed significantly from the original design
How should I put this? We here also have CNTH cold containers, and the same issue has occurred there as well
Perhaps the low methane content results in poor heat exchange efficiency in the second feed cooler, causing the cold flow to move upward, which increases the amount of nitrogen used for washing and reduces the amount of nitrogen used in the preliminary preparation stage. Increasing the amount of gas removed from synthesis to bring back the cooling capacity to the system might help
This situation also occurs at Hangyang Oxygen; it happens when the load is low and there is an excess of cooling capacity
What type of vaporizer do you have? How much liquid nitrogen is needed to wash methane? ?
What type of vaporizer do you have? How much liquid nitrogen is needed to wash methane?
What kind of vaporizer is the poster using? How much liquid nitrogen is needed to wash methane?