The issue of LNG production volume increase after adding CNG refueling stations in the LNG production process
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Our facility uses a mixed-refrigerant process; a connection is made from the natural gas pipeline (at around 40 bar) after the drying unit to the CNG compressor, in order to fill the CNG tankers. However, the arrival time of these CNG tankers is not fixed, which results in unstable pressure in the LNG production system and affects the amount of LNG produced. What measures can be taken during the production process to reduce the impact of CNG filling on the system? I would also appreciate your valuable advice.
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Was this low-load operating condition not taken into account during the liquefaction design?
Is it okay for you guys to play like this? It definitely has an impact on the stability of LNG production; it’s not possible to completely eliminate that impact
The impact is quite significant; for now, the only option is to stop the CNG operation in order to raise the temperature of the second stage of the refrigerant compressor, but it seems that this approach doesn’t have much effect. I’m looking for a better solution.
I’m not quite sure; is that what it means? Is the pressure used for LNG liquefaction unstable after drying? In other words, the process system was not designed considering the most unfavorable operating conditions. What parameter fluctuations can occur if CNG is not refilled? Pressure and flow rate? Natural gas entering the station is merely for transportation; the flow rate and pressure depend entirely on the amount of gas taken out later. What effects will there be if CNG is not filled? It’s not that the capacity is large. Could you explain it?
You know about the LNG production system, right? Pipes are taken from the entire system to the CNG compressor, and the CNG compressor is not always running. When it starts, it generates high suction force, causing pressure fluctuations in the LNG system, which affects production volume and power consumption.
If the design was based on full load conditions and the pressure fluctuations occur only when the machine is started up, then it’s entirely possible to solve this issue by installing a sufficiently large buffer tank in front of the compressor! If the design did not take into account the use of CNG, then there is no way to resolve the problem fundamentally; the only option is to reduce the number of compressors in use in order to lessen the amount of compression work that needs to be done
CNG was not taken into consideration during the design at that time
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