Output issues of ethylene tanks at normal pressure and low temperature
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A 20,000 m3 ethylene tank at normal pressure and low temperature, with bottom discharge; it uses buried barrel pumps (from German company Hermle). The liquid level of these pumps fluctuates frequently. I would like to ask if anyone has experience in this area and knows what might be causing such issues! Thank you!!
Currently, there are over 10 facilities in China for the production of propylene, LNG, and ethylene under normal pressure and low temperatures. Is there no expert who understands this field?
What does it mean when the liquid level of the pump fluctuates frequently? Generally, the liquid level of the medium stored in low-temperature tanks remains very stable. Please explain.
I work in cryogenic engineering as well; I’m here to introduce myself
I was on a business trip for 4 days and haven’t returned yet – my apologies! A barrel pump, also known as a submersible pump, is used in this case; low-temperature ethylene tends to vaporize easily. If a regular pump were used, cavitation would occur frequently. Continuous operation isn’t a problem, but starting the pump can be difficult. Level fluctuations refer to the drop in the liquid ethylene level inside the pump barrel. When this level reaches a set value, to prevent the pump from running dry and getting damaged, the pump will be shut down automatically through interlock mechanism. While the pump is thus protected, the downstream equipment will have to stop operating as well!!
I didn’t see it clearly just now! The liquid level in the tank is stable; I’m referring to the liquid level of the output pump!!
1. Before starting the pump, the pipeline at the pump inlet should be depressurized. 2. If liquid level fluctuations during operation cause the pump to stop automatically as a result of interlocks, I believe the design is not thorough enough. First, a pipeline should be connected to the gas phase on the main extraction line of the low-temperature tank, so as to ensure that the gas generated by the extraction line returns to the large tank in a timely manner. Secondly, the pump inlet pipeline should also have a dedicated line to collect the gas generated, which will essentially ensure that the pump does not stop operating. Of course, a too low liquid level in the cryogenic tank is another matter.
There are many reasons; here are a few brief explanations: (1) There is an issue with the installation height of the pump’s suction inlet. (2) The flow rate is too low, and the pressure buildup causes ethylene to vaporize. (3) The pump has poor heat insulation. (4) The pump was not adequately pre-cooled before startup.
It is recommended to connect the pump’s exhaust line directly to the inlet of the ethylene compressor; this way, the pump will not suffer from cavitation
I have worked at the ethylene plant for 7 years; low liquid levels are caused by cavitation. When the liquid level is low, manual venting is required. Another reason is that an excessively low liquid level in the large tank can cause problems! !
I would like to ask if you know how much it costs to invest in an ethylene storage tank with a capacity of 30,000 cubic meters. What is the typical design of ethylene storage tanks, and could you provide their dimensions?
20,000 cubic meters, 55 million – cylindrical
It has a diameter of about 33 meters and a height of around 31 meters
May I ask what the operating parameters of this pump are, OP? Are pumps imported from Germany being used?