Ok finally i found the problem why my natural Gas compressors filter shows high DP when LNG tanker filling starts.
Operating Range or General Conditions :
Suction Temperature : -135 to -145 Deg C
Pressure : 100-200 mbarg
Problem 1)
Problem Arises when Vapour return from LNG tanker (truck) meets with Gas from Storage Tanks leads to increase in BOG Compressor suction temperature to -130 to -110 deg C . in this region Compressor suction filter reading shows very high .
Since Truck loading frequency is very high in our terminal having 4 bays of truck loading , so BOG suction temperature of compressors keeps on getting high and high unless Tanker filling to be stopped forcefully.
Truck is completely moisture free , hydrates free , always came with some heel .
Problem 2)
which is quite strange !
with Vendor A: LNG truck came with Pressure 7-8 barg. When equalising the truck pressure with our vapour line , vapour line temperature reaches -80 to -130 Deg C
But with vendor B : truck with same pressure , when equalising vapour temperature reaches somehow -20 to -50 deg C and when tanker filling completed still vapour return temperature does not able to reach -100 sometimes.
We are having doubt with vacuum insulation of LNG trucks of vendor B.